The plant is in perfect condition (4)
I believe the answer is:
mint
I believe this clue is a double definition.
'the plant' is the first definition.
(mint is a kind of plant)
'perfect condition' is the second definition.
(I've seen this before)
'is in' is the link.
(Other definitions for mint that I've seen before include "Plant - in perfect condition" , "Vast sum of money" , "Produce coins" , "Culinary herb" , "Aromatic herb - perfect" .)