Fighting bears with a sword (5)
I believe the answer is:
sabre
'sword' is the definition.
(I know that sabre is a type of sword)
'fighting bears' is the wordplay.
'fighting' indicates anagramming the letters.
'bears' anagrammed gives 'SABRE'.
'with a' is the link.
(Other definitions for sabre that I've seen before include "Sword (that may be rattled)" , "weapon" , "Heavy cavalry sword" , "Type of sword" , "Sword with curved blade" .)