Variety of celery with a large turnip-like root (8)
I believe the answer is:
celeriac
(Other definitions for celeriac that I've seen before include "Plant with turnip-like root" , "Whitish root vegetable" , "Edible root for Alec Rice" , "Plant with a turnip-like 1 down" , "Clear ice (anag) - it is used as a vegetable" .)