Variable land, fine after tilling to produce grape variety (9)
I believe the answer is:
zinfandel
'grape variety' is the definition.
(I've seen this before)
'variable land fine after tilling' is the wordplay.
'variable' becomes 'z' (algebra).
'after tilling' is an anagram indicator (letters must be worked over or tilled).
'land'+'fine'='landfine'
'landfine' with letters rearranged gives 'infandel'.
'z'+'infandel'='ZINFANDEL'
'to produce' is the link.
(Other definitions for zinfandel that I've seen before include "Californian wine grape" , "Dry wine" , "blush" , "Californian grape variety" , "Black grape grown in California" .)