Fish named for a weapon (4)
I believe the answer is:
pike
'fish named for a weapon' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for pike that I've seen before include "Predator with strong teeth" , "See 1 down" , "may be hooked" , "Former infantry weapon" , "Fish - old infantry weapon" .)