Fighting female concealing a warm heart (6)
I believe the answer is:
karate
'fighting' is the definition.
The definition and answer can be both acts as well as being singular nouns.
Perhaps you can see a link between them that I don't see?
'female concealing a warm heart' is the wordplay.
'female' becomes 'kate' (I am not sure about this - if you are sure you should believe this answer much more).
'concealing' indicates putting letters inside.
'heart' indicates the central letters.
The central letters of 'warm' are 'ar'.
'kate' enclosing 'ar' is 'KARATE'.
Can you help me to learn more?
(Other definitions for karate that I've seen before include "Oriental-style chops" , "Martial art (with chopping?)" , "Unarmed-combat system" , "A taker (anag)" , "SPORT/GAME" .)