Heaviest fencing weapon (4)
I believe the answer is:
epee
'heaviest fencing weapon' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for epee that I've seen before include "Sharp-pointed duelling sword" , "Thin fencing sword" , "Fencer's weapon" , "Pointed weapon" , "Type of sword" .)