The most common and most likely answer to this crossword clue is the 5 letter word COMIC
I've seen this crossword clue in The Guardian
C
O
M
I
C
More clues leading to the result COMIC
- Comedian in panic, I'm occasionally laid back
- Stand-up maybe needing company microphone
- Funny performer in company, taking microphone briefly
- Stand-up artist perhaps of vast size hasn't succeeded
- Funny pear’s not English
- Pear with no end is highly amusing
- Rich judge accommodates press for charity event
- Dandy perhaps stuffs old note in volume
- Cause of cracks that can bring down the house
- Rich Saunders?
Buddy explains!

The straight part
We know that "Wag" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case wag = comic.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does COMIC mean?
COMIC noun- A comedian.
- A story composed of cartoon images arranged in sequence, usually with textual captions; a graphic novel.
- A children's newspaper.
- Funny; amusing; comical.
- Relating to comedy.