Gents maybe endlessly promiscuous (4)
I believe the answer is:
loos
'gents maybe' is the definition.
(gents toilets)
'endlessly promiscuous' is the wordplay.
'endlessly' means to remove the last letter.
'promiscuous' becomes 'loose' (loose can mean promiscuous).
'loose' with its last letter taken away is 'LOOS'.
(Other definitions for loos that I've seen before include "Austrian architect" , "Conveniences" .)