Part of magic act uses plant (6)
I believe the answer is:
cactus
'plant' is the definition.
(cactus is a kind of plant)
'part of magic act uses' is the wordplay.
'part of' indicates the answer is hidden within the clue.
'CACTUS' is hidden within 'magic act uses'.
(Other definitions for cactus that I've seen before include "Spiky desert plant" , "Thorny desert plant" , "Prickly desert plant" , "Prickly sort" , "Spiny plant of dry regions" .)