What thief does in police stations? (5)
I believe the answer is:
nicks
'does in police stations?' is the definition.
The definition and answer can be both related to bodily activities as well as being verbs in their -s form.
Perhaps you can see an association between them that I don't see?
I cannot understand how the remainder of the clue works.
(Other definitions for nicks that I've seen before include "US singer "Stevie"" , "Prisons (sl.)" , "Pinches or makes a small cut" , "Arrests (slang)" , "Steals (sl.)" .)