Cryptic crosswords are famously difficult to learn because they have their own logic that you kind of need someone to teach you before you can participate. They're kind of like a Rubik's Cube, in that if you don't know anything about how it works it seems totally impossible, but with a little basic instruction most people can participate on some level.
I'm going to use https://www.minutecryptic.com/ puzzles over this week to teach anyone interested how to think about cryptic clues (unless this post sinks like a stone haha). I happen to have had several different friends who would take the time to explain to me how to read clues and then we'd solve them together. I'm going to explain how to read the above clue and let anyone who wants try to guess the answer (you can just follow the link and they'll give you successive hints, it's a good site for learning honestly.) I will spoiler tag any hints.
THE BASICS
THE STRAIGHT CLUE:
Every cryptic clue has a word or string of words at the beginning or end (but never in the middle) of the clue that acts like a regular crossword clue. In the case of this clue we know from the start that we're looking for a 4-letter word that either means "little", "little bit", "little bit of whisky" or "the morning". This part of the clue is ALWAYS unrelated to the 'wordplay' part of the clue:
THE WORDPLAY:
The rest of the clue offers some way to create the answer to the straight clue by chopping up, rearranging and concatenating the other words in the clue (or their synonyms). This section can be much looser and obeys a series of different types of rules.
For example, a clue may ask you to make an anagram of an adjacent word (or words) by using an 'indicator' word like 'mixed up', 'crazy', 'damaged', 'in a storm', etc. (This is often the easiest indicator for beginners, as once you get a sense there may be an anagram indicator, the next step would be to count letters in the words adjacent to the indicator and compare them to the letters in the answer.) Other types of indicators might suggest you remove letters from an adjacent word ('headless' may indicate removing the first letter, 'naked' might suggest removing the outer letters, etc) or put something inside a word ('containing' or 'protects' might suggest the preceding string would surround the following string to create the answer) and so on.
A little bit of whisky? Not at two in the morning!
I couldn't decide what the straight clue could be, (a 4-letter word that either means "little", "little bit", "little bit of whisky" or "the morning") as I could think of 4-letter words for all of them. So I started with the wordplay.
There are many kinds of words that can be substituted by a common abbreviation. "Time" can be substituted for "t" like in physics, "University" can be substituted with "U" as in "UCLA", etc. We have two of these in our clue:
spoiler
"whisky" is a letter in the phonetic alphabet representing a "W" as in "whisky tango foxtrot", and "the morning" can be replaced with "AM".
Next to the indicators - this clue has two of these as well.
spoiler
"Not at" is a very loose deletion indicator, so "Whisky not at two" suggests the "W" is "not at" the word "two", so we remove the "W" from "two".
The word
spoiler
"in" is a wordplay indicator implying containment, like a term preceding it should be placed within a term for "the morning". So "two in the morning" might normally indicate placing the word "two" between the letters of "AM" but remember the previous indicator suggested we delete the "W".
Lastly we look back at our clue and see the words not involved in the wordplay are at the start, and must be our straight clue:
spoiler
"Little bit",
spoiler
"little bit", and you get it by removing the "W" from "two" and putting that in "AM".
If you just want the answer you can click the link above, they supply incremental hints (and in this case an alternative clue), and they supply good explainer videos that explain the reasoning of the puzzle assuming you've already learned the answer, but if you want to have a go you can have a guess and I can tell you if you're right, but usually once you get the answer you know it's correct because it satisfies both parts of the clue.
In the comments of their explainer video, they issued a little kind of apology some people didn't like this clue, thought it was a bit too loose. I tend to agree as this site is supposed to be for beginners.
