Part of The Square sustainably set up for the consumer (4)
I believe the answer is:
user
'the consumer' is the definition.
(user is a kind of consumer)
'part of the square sustainably set up' is the wordplay.
'part of' indicates a hidden word.
'set up' shows that the letters should be reversed in order.
'resu' is hidden within 'square sustainably'.
'resu' reversed gives 'USER'.
'for' acts as a link.
(Other definitions for user that I've seen before include "Drug-taker" , "Utiliser" , "With 1a [NEW] he'll need different login" , "One who works an appliance" , "Drug addict (colloq.)" .)