Average cut for Root (7)
I believe the answer is:
parsnip
'root' is the definition.
(parsnip is a kind of root)
'average cut' is the wordplay.
'average' becomes 'par' (average score in golf).
'cut' becomes 'snip' (snipping is a kind of cutting).
'par'+'snip'='PARSNIP'
'for' is the link.
(Other definitions for parsnip that I've seen before include "Sweet root vegetable" , "Plant with edible white root" , "Pips ran oddly through the vegetable" , "food" , "Tapering vegetable" .)