Uppity veteran sneakily hides trap (7)
I believe the answer is:
ensnare
'trap' is the definition.
(to ensnare is to trap or capture)
'uppity veteran sneakily hides' is the wordplay.
'uppity' is a reversal indicator (in a down clue, words go 'up').
'hides' indicates a hidden word.
'eransne' is hidden within 'veteran sneakily'.
'eransne' written backwards gives 'ENSNARE'.
(Other definitions for ensnare that I've seen before include "Ecstatic expression of feeling" , "Ambush" , "Catch as if in a trap or net" , "Capture, trap" .)