One’s bound by others to put up a fight (6)
I believe the answer is:
resist
'put up a fight' is the definition.
(I've seen this before)
'one's bound by others' is the wordplay.
'one's' becomes 'is' (roman numeral).
'bound by' indicates putting letters inside (I've seen this in other clues).
'others' becomes 'rest' (I've seen this before**).
'is' inserted inside 'rest' is 'RESIST'.
'to' acts as a link.
(Other definitions for resist that I've seen before include "Oppose or fight against someone" , "Use force to prevent something from happening to sister" , "Bar" , "Withstand, struggle against" , "Oppose, put up defence" .)