Mean the i, small, should be a capital (5)
I believe the answer is:
paris
'a capital' is the definition.
(capital of France)
'mean the i small' is the wordplay.
'mean' becomes 'par' (average score on a golf course).
'small' becomes 's' (abbreviation - e.g. clothes size).
'par'+'i'+'s'='PARIS'
'should be' is the link.
(Other definitions for paris that I've seen before include "Eiffel Tower city" , "European capital city" , "where he got plastered?" , "European capital - Greek hero" , "Capital of France" .)