Graham ___, former member of The Hollies best known for his collaboration with David Crosby and Stephen Stills (4)
I believe the answer is:
nash
(Other definitions for nash that I've seen before include "Famous dandy, Beau --" , "Beau --. Ogden --" , "John -, Eng. architect" , "Ogden -, US poet, wit" , "English architect, d. 1835 - English war artist, d. 1946" .)