Finally, another straight-forward cryptic clue! (Through some bad luck we haven't had one since Day 1)
See Day 2 here (&lit clue)
See Day 3 here (too hard)
See Day 4 here (Dual Definition clue)
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'd normally looking for a with a 3-letter word that either means "20/20", "20/20 vision", "eye patch" or "eye". 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.
20/20 vision eye patch
Finally back to normal cryptic clues that are good for beginners. If you've been following along, you might be able to get this from the straight clue alone, even though we haven't seen this type of wordplay indicator before.
The wordplay indicator here is
spoiler
"patch", which is a "hidden word" indicator, implying there is a word that 'patches together' two (or more) other adjacent words. (This is not a very common hidden word indicator, more common is something like "conceals".) An example I saw recently was "Blackbeard rumoured" has the hidden word "eardrum".
Since there are only 4 "words" to the clue, and
spoiler
"patches" requires at least the nearest two words, this means our straight clue has to be "20/20".
So we're looking for a 3-letter word that means
spoiler
"20/20" that can also be found connecting the words "vision eye".
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, 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.
