Pacifist in America jumped off cliff (4)
I believe the answer is:
Here is my best explanation:
This clue is a double definition.
'pacifist' is the first definition.
(dove is a kind of pacifist)
'in america jumped off cliff' is the second definition.
(past tense of 'dive' in American English)
(Other definitions for dove that I've seen before include "Bird; advocate of peace", "Mourning, collared, bird", "(Peaceful) bird", "Bird representing peace", "Pigeon-like bird", "The bird of peace", "Peaceful type", "A peaceful bird?", "So-called pacifist" and "Small pigeon".)