Many split hairs about it being a vegetable (6)
I believe the answer is:
radish
'a vegetable' is the definition.
(radish is a type of vegetable)
'many split hairs about it' is the wordplay.
'many' becomes 'D' (Roman numeral for 500).
'split' indicates an anagram (letters split up and reassembled).
'about it' is an insertion indicator (some letters go around or about others).
'hairs' with letters rearranged gives 'raish'.
'd' inserted within 'raish' is 'RADISH'.
'being' acts as a link.
(Other definitions for radish that I've seen before include "Daikon or mooli" , "Hottish salad plant" , "Red cold salad ingredient" , "Bit of salad" , "Root vegetable used in salads" .)