The most common and most likely answer to this crossword clue is the 6 letter word TELSON
T
E
L
S
O
N
Buddy explains!
The straight part
We know that "a bit “crabby”?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case a bit “crabby”? = telson.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 TELSON mean?
TELSON noun- The part of an arthropod or crustacean posterior to the last segment.