Spiny desert plant (6)
I believe the answer is:
cactus
'spiny desert plant' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for cactus that I've seen before include "Spiney plant of dry regions" , "plant, succulent one" , "Spiny plant of dry regions" , "Succulent desert plant" , "Plant found in dry places" .)