Composer brings perfect happiness (5)
I believe the answer is:
bliss
I believe this clue is a double definition.
'composer' is the first definition.
(British composer Arthur Bliss)
'perfect happiness' is the second definition.
(I've seen this before)
'brings' acts as a link.
(Other definitions for bliss that I've seen before include "Cloud nine" , "One who scored" , "Great joy" , "Serene joy" , "Felicity" .)