Fashion line for Cara Delevingne, say (5)
I believe the answer is:
model
'cara delevingne say' is the definition.
(I know that Cara Delevingne has the occupation supermodel)
'fashion line' is the wordplay.
'fashion' becomes 'mode' (synonyms).
'line' becomes 'l' (used when specifying particular lines from a poem).
'mode'+'l'='MODEL'
'for' is the link.
(Other definitions for model that I've seen before include "Example (on the catwalk?)" , "Clothes displayer" , "Moss, say" , "Fashion - prototype" , "A displayer of fashions" .)