I want a rook to fly like a dove (7)
I believe the answer is:
antiwar
'like a dove' is the definition.
(dove can mean an advocate of peace)
'i want a rook to fly' is the wordplay.
'rook' becomes 'r' (abbreviation in chess).
'to fly' indicates anagramming the letters.
'i'+'want'+'a'+'r'='iwantar'
'iwantar' anagrammed gives 'ANTIWAR'.
(Other definitions for antiwar that I've seen before include "of the Pacific class" , "like a dove" , "Opposed to hostilities" , "Promoting peace" , "opposed to aggression" .)