Anything seized? Not cocaine (5)
I believe the answer is:
aught
'anything' is the definition.
(I've seen this before)
'seized? not cocaine' is the wordplay.
'seized?' becomes 'caught' (catching is a kind of seizing).
'not' suggests deleting specific letters.
'cocaine' becomes 'C' (drugs abbreviation).
'caught' with 'c' removed is 'AUGHT'.
(Other definitions for aught that I've seen before include "Nothing" , "Anything (Shakespearean)" , "Anything at all (archaic)" , "Emphatically anything" .)