Bird lost height quickly over the pond (4)
I believe the answer is:
I believe this clue is a double definition.
'bird' is the first definition.
(I know that dove is a type of bird)
'lost height quickly over the pond' is the second definition.
(past tense of 'dive' in US English)
(Other definitions for dove that I've seen before include "Cooing bird" , "So-called pacifist" , "Symbol of peace" , "Peaceful type" , "Bird; advocate of peace" .)