Decay seen in small green vegetable and shrub (6)
I believe the answer is:
protea
'shrub' is the definition.
(protea is a kind of shrub)
'decay seen in small green vegetable' is the wordplay.
'decay' becomes 'rot' (rot is a kind of decay).
'seen in' is an insertion indicator.
'small green vegetable' becomes 'pea'.
'rot' placed within 'pea' is 'PROTEA'.
'and' acts as a link.
(Other definitions for protea that I've seen before include "South African evergreen" , "South African shrub" , "Ascend" , "S. African shrub; to pear (anag.)" , "S.African flowering shrub" .)