Mean criminal head in police force set free (11)
I believe the answer is:
emancipated
'set free' is the definition.
(I've seen this before)
'mean criminal head in police' is the wordplay.
'criminal' indicates anagramming the letters.
'head' becomes 'pate' (humorous term for the head).
'in' means one lot of letters goes inside another.
'police' becomes 'CID' (abbreviation for Criminal Investigation Department).
'pate' put within 'cid' is 'cipated'.
'mean' is an anagram of 'eman'.
'eman'+'cipated'='EMANCIPATED'
'force' is the link.
This may not be correct. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for emancipated that I've seen before include "free from constraints" , "Set free" , "Freed from slavery" .)