Ancient Greek city, in North, I suspect, by Cape (7)
I believe the answer is:
corinth
'ancient greek city' is the definition.
(I've seen this before)
'north i suspect by cape' is the wordplay.
'suspect' indicates anagramming the letters.
'by' says to put letters next to each other.
'cape' becomes 'c' (abbreviation used on maps).
'north'+'i'='northi'
'northi' with letters rearranged gives 'orinth'.
'orinth' put after 'c' is 'CORINTH'.
'in' acts as a link.
(Other definitions for corinth that I've seen before include "Region of ancient Greece" , "Greek Gulf, isthmus city" , "Mediterranean port" , "City of Greece" , "Ancient Greek city" .)