Whaling weapon (7)
I believe the answer is:
harpoon
'whaling weapon' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for harpoon that I've seen before include "Whaling weapon" , "whaling equipment" , "Whaler's weapon" , "Anti-whale weapon" , "Whaler's spear" .)