Sedated criminal is determined (4-3)
I believe the answer is:
dead set
'is determined' is the definition.
(I've seen this before)
'sedated criminal' is the wordplay.
'criminal' indicates an anagram.
'sedated' with letters rearranged gives 'DEAD-SET'.
(Other definitions for dead set that I've seen before include "Bent on - sedated (anag)" , "Determined (upon)" , "Fully determined" , "Fixed in one's purpose" , "Absolutely - sedated (anag)" .)