Fix up label or it might snap (5)
I believe the answer is:
gator
'it might snap' is the definition.
The definition suggests a singular noun which matches the answer.
'fix up label or' is the wordplay.
I cannot really understand how this works, but
'or' is present in the answer.
The remaining letters 'gat' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for gator that I've seen before include "Crocodilian (informal)" , "Informal American term for semi-aquatic reptile" , "beast?" , "one snaps in America" , "Short reptile" .)