Footballer, about to be dropped by United or City (4)
I believe the answer is:
baku
'city' is the definition.
(capital of Azerbaijan)
'footballer about to be dropped by united' is the wordplay.
'footballer' becomes 'back' (back is a kind of footballer).
'about to be' becomes 'c' (I've seen this in other clues).
'dropped' indicates named letters should be taken away (some letters are excluded or dropped).
'by united' becomes 'u' (as in Man U, English football team. I am not sure about the 'by' bit.).
'back' with 'c' taken away is 'bak'.
'bak'+'u'='BAKU'
'or' is the link.
(Other definitions for baku that I've seen before include "Capital of Azerbaijan on shore of Caspian Sea" , "Caspian Sea port" , "Capital city of Azerbaijan" , "Azerbaijan's capital" .)