Enhancement for viewers almost crazy to get odd vegetable (8)
I believe the answer is:
kohlrabi
'odd vegetable' is the definition.
(unusual vegetable)
'enhancement for viewers almost crazy' is the wordplay.
'enhancement for viewers' becomes 'kohl' (make-up for eyes ie 'viewers').
'almost' means to remove the last letter (most of the word but not all of it).
'crazy' becomes 'rabid' (I've seen this before).
'rabid' with its final letter taken away is 'rabi'.
'kohl'+'rabi'='KOHLRABI'
'to get' acts as a link.
(Other definitions for kohlrabi that I've seen before include "leaves to be consumed" , "Variety of cabbage like a turnip" , "vegetable" .)