Spear fish (4)
I believe the answer is:
pike
This clue is a double definition.
'spear' is the first definition.
(I know that pike is a type of lance)
'fish' is the second definition.
(pike is a kind of fish)
(Other definitions for pike that I've seen before include "Weapon on long shaft; Northern hill" , "Predator with strong teeth" , "Voracious freshwater fish" , "dive in this position" , "Fish - long spear-like weapon" .)