Married or single (3)
I believe the answer is:
one
I believe this clue is a double definition.
'married' is the first definition.
(I've seen this in another clue)
'single' is the second definition.
(I know that single can be written as one)
'or' is the link.
(Other definitions for one that I've seen before include "If upper-class, perhaps I" , "Lowest cardinal number" , "A certain; single person" , "Figure" , "I can mean this" .)