Man united, somehow, with a single relative (6,4)
I believe the answer is:
maiden aunt
'single relative' is the definition.
(I've seen this before)
'man united somehow with a' is the wordplay.
'somehow with' is an anagram indicator.
'man'+'united'='manunited'
'manunited' with its letters mixed up with 'a' gives 'MAIDEN AUNT'.
(Other definitions for maiden aunt that I've seen before include "single relative" , "single female" .)