One-nil for United?
I believe the answer is:
in one
'united?' is the definition.
(I've seen this before)
'one-nil' is the wordplay.
'one' becomes 'i' (Roman numeral).
'nil' becomes 'none' (I've seen this before).
'i'+'none'='IN ONE'
'for' is the link.
(Other definitions for in one that I've seen before include "A hole . . . . . is a singular golf score" , "As a single unit" , "united" , "Combined" .)