Software customer (4)
I believe the answer is:
user
'software customer' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for user that I've seen before include "With 1a [NEW] he'll need different login" , "Manipulative woman" , "Right long-established" , "Exploiter (of others)" , "Drug taker" .)