… partly for a chemical plant (6)
I believe the answer is:
orache
'plant' is the definition.
(orache is a kind of plant)
'partly for a chemical' is the wordplay.
'partly' indicates a hidden word.
'ORACHE' is hidden in the letters of 'for a chemical'.
(Other definitions for orache that I've seen before include "Edible spinach-like plant of the genus Atriplex that thrives in arid areas" , "spinach substitute" , "vegetable" .)