Devil seen in former police station? (3,4)
I believe the answer is:
old nick
'devil' is the definition.
(I know that devil can be written as Old Nick)
'former police station?' is the wordplay.
'former' becomes 'old' (both can mean previous).
'police station?' becomes 'nick' (slang term).
'old'+'nick'='OLD NICK'
'seen in' acts as a link.
(Other definitions for old nick that I've seen before include "The Evil One" , "Newgate for instance" , "alternative to deep blue sea" , "'The prince of darkness (3,4)'" , "cut from long ago?" .)