Man United! (7)
I believe the answer is:
husband
'man' is the definition.
(someone's man could mean their husband)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for husband that I've seen before include "Better half's other half?" , "Woman's matrimonial partner" , "Farm" , "Use (resources) thriftily" , "Partner; use carefully" .)