One's yellow jersey, perhaps, found on a road (6)
I believe the answer is:
'one's yellow' is the definition.
(yellow can mean cowardly)
'jersey perhaps found on a road' is the wordplay.
'jersey perhaps' becomes 'cow' (Jersey is a breed of cow).
'found on' means one lot of letters go next to another.
'road' becomes 'rd' (abbreviation for road).
(Other definitions for coward that I've seen before include "Author of 'Blithe Spirit'" , "Mad Dogs and Englishmen songwriter" , "Craven type" , "Faint-hearted person" , "Noel ..... composed musical 'Bitter Sweet'" .)