Old women into gang fighting (6)
I believe the answer is:
rowing
'fighting' is the definition.
(to row is to argue)
'old women into gang' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'women' becomes 'w'.
'into' indicates putting letters inside.
'gang' becomes 'ring' (synonyms).
'o'+'w'='ow'
'ow' inserted into 'ring' is 'ROWING'.
(Other definitions for rowing that I've seen before include "Aquatic sport" , "Sport associated with Henley" , "Using oars" , "Olympic event" , "Olympic sport; arguing" .)