Combat is contained in the others (6)
I believe the answer is:
resist
'combat' is the definition.
(I've seen this before)
'is contained in the others' is the wordplay.
'contained in' indicates putting letters inside.
'the others' becomes 'rest' (I've seen this in another clue).
'is' inserted inside 'rest' is 'RESIST'.
(Other definitions for resist that I've seen before include "Express opposition" , "Forgo" , "Withstand, struggle against" , "Hold out for sister" , "Offer opposition to" .)