Carrot's cousin (7)
I believe the answer is:
parsnip
'carrot's cousin' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for parsnip that I've seen before include "Tapering vegetable" , "A white root vegetable" , "Plant with edible white root" , "Spar pin (anag) - vegetable" , "Sweet root vegetable" .)