The most common and most likely answer to this crossword clue is the 2 letter word AH
A
H
Buddy explains!

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 AH mean?
AH pronoun- The speaker or writer, referred to as the grammatical subject, of a sentence.
- The speaker or writer, referred to as the grammatical object, of a sentence.
- An instance of the interjection ah.
- To give a cry of "ah".
- An expression of relief, relaxation, comfort, confusion, understanding, wonder, awe, etc. according to uttered inflection.
- A syllable used to fill space, particularly in music.