Exact force, capturing City area (7)
I believe the answer is:
precise
'exact' is the definition.
(I know that exact can be written as precise)
'force capturing city area' is the wordplay.
'force' becomes 'prise' (I've seen this before).
'capturing' means one lot of letters goes inside another.
'city area' becomes 'EC' (EC is a London postcode area).
'prise' placed around 'ec' is 'PRECISE'.
(Other definitions for precise that I've seen before include "Exact like recipes" , "Express" , "Highly accurate and sharply exact" , "with accuracy" , "Detailed, exact" .)