Try endless fighting to gain grip (8)
I believe the answer is:
traction
'grip' is the definition.
(I know that grip can be written as traction)
'try endless fighting' is the wordplay.
'endless' means to remove the last letter.
'fighting' becomes 'action' (as in military action).
'try' with its final letter removed is 'tr'.
'tr'+'action'='TRACTION'
'to gain' acts as a link.
(Other definitions for traction that I've seen before include "Grip between something and the surface on which it moves" , "Use of weights and pulleys to heal a fracture" , "Pulling power" , "Medical stretching" , "Grip - rat in cot (anag)" .)