Controversial, police working with Frenchman (7)
I believe the answer is:
polemic
'controversial' is the definition.
(similar in meaning)
'police working with frenchman' is the wordplay.
'working with' is an anagram indicator (working with the letters).
'frenchman' becomes 'M' (abbreviation for Monsieur - like 'Mr').
'police' mixed up with 'm' gives 'POLEMIC'.
(Other definitions for polemic that I've seen before include "Controversial writing or oratory" , "tirade" , "Fierce spoken or written attack" , "Fierce argument that attacks or defends an idea" , "Contentious" .)