To finish, I have a salad plant (6)
I believe the answer is:
endive
'a salad plant' is the definition.
(I've seen this before)
'to finish i have' is the wordplay.
'to finish' becomes 'end' ('end' can be a synonym of 'finish').
'i have' becomes 'ive'.
'end'+'ive'='ENDIVE'
(Other definitions for endive that I've seen before include "Envied (anag.)" , "salad ingredient" , "Veined (anag) - salad plant" , "Envied the salad green badly" , "Edible plant" .)