Servant pinching doctor's capital (6)
I believe the answer is:
madrid
'capital' is the definition.
(Madrid is an example)
'servant pinching doctor's' is the wordplay.
'servant' becomes 'maid' (maid is a kind of servant).
'pinching' means one lot of letters goes inside another (taking inside).
'doctor' becomes 'dr' ('Dr' can be a synonym of 'doctor').
'maid' enclosing 'dr' is 'MADRID'.
(Other definitions for madrid that I've seen before include "European capital city" , "Spanish city" , "City with the Prado national art gallery" , "Capital of Spain since 1561" , "Spanish capital" .)