Couple needing space after sex (4)
I believe the answer is:
item
'couple' is the definition.
(I've seen this before)
'space after sex' is the wordplay.
'space' becomes 'em' (in typography, a space as wide as a letter 'm').
'after' says to put letters next to each other.
'sex' becomes 'it' (a common euphemism).
'em' put after 'it' is 'ITEM'.
'needing' acts as a link.
(Other definitions for item that I've seen before include "Report" , "Individual object" , "Record" , "Boyfriend and girlfriend" , "A thing or unit" .)