Lock in criminal at chokey (5)
I believe the answer is:
latch
'lock' is the definition.
(thesaurus)
'in criminal at chokey' is the wordplay.
'in' indicates a hidden word.
'LATCH' is hidden in the letters of 'criminal at chokey'.
(Other definitions for latch that I've seen before include "Light door lock" , "Gate bar" , "Door-fastening" , "Gate fastener" , "Something to secure" .)