Seize prisoner - fit case another way (10)
I believe the answer is:
confiscate
'seize' is the definition.
(I know that seize can be written as confiscate)
'prisoner fit case another way' is the wordplay.
'prisoner' becomes 'con' (abbreviation for 'convict').
'another way' is an anagram indicator.
'fit'+'case'='fitcase'
'fitcase' with letters rearranged gives 'fiscate'.
'con'+'fiscate'='CONFISCATE'
(Other definitions for confiscate that I've seen before include "Take control of" , "Seize as penalty - facts on ice (anag)" , "Impound" , "Take away (property)" .)