Managed a branch of the UK Police Force, has become stale (6)
I believe the answer is:
rancid
'stale' is the definition.
(similar in meaning)
'managed a branch of the uk police force has' is the wordplay.
I cannot quite understand how this works, but
'managed' could be 'ran' (I've seen this before) and 'ran' is found in the answer.
'police' could be 'cid' (abbreviation for Criminal Investigation Department) and 'cid' is found in the answer.
No letters remain.
This explanation may well be incorrect...
'become' acts as a link.
Can you help me to learn more?
(Other definitions for rancid that I've seen before include "(Of fatty foods) stale" , "Smelling bad like stale fat" , "No longer fresh" , "Unpleasantly stale" , "Rank-smelling." .)