Nothing gets over pass ahead of northern city (7)
I believe the answer is:
lincoln
'city' is the definition.
(Lincoln is an English city)
'nothing gets over pass ahead of northern' is the wordplay.
'nothing' becomes 'nil' (eg nil is zero in football).
'gets over' shows that the letters should be reversed in order (I've seen 'got over' mean this).
'pass' becomes 'col' (col is a term for a mountain pass).
'ahead of' is a charade indicator (letters next to each other) (some letters go in front of others).
'northern' becomes 'n' (abbreviation e.g. N. Ireland).
'nil' reversed gives 'lin'.
'lin'+'col'+'n'='LINCOLN'
(Other definitions for lincoln that I've seen before include "City on River Witham" , "US president who gave Gettysburg Address" , "US car marque" , "The first green" , "16th President of the United States" .)