Louts vandalised plant (5)
I believe the answer is:
lotus
'plant' is the definition.
(lotus is a kind of plant)
'louts vandalised' is the wordplay.
'vandalised' indicates anagramming the letters.
'louts' with letters rearranged gives 'LOTUS'.
(Other definitions for lotus that I've seen before include "Plant that mythically induces languor" , "Water lily - fruit inducing forgetfulness" , "Water-lily; yoga position" , "reason for indolence" , "Mythical fruit inducing state of luxurious dreaminess" .)