Component of dive to get fish (4)
I believe the answer is:
pike
I believe this is a double definition.
'component of dive' is the first definition.
(position in diving)
'fish' is the second definition.
(pike is a kind of fish)
'to get' is the link.
(Other definitions for pike that I've seen before include "Weapon on long shaft; Northern hill" , "Spearhead attached to a long pole" , "Former infantry weapon" , "may be hooked" , "Predatory freshwater fish" .)