Celebrated artist nursing one drink in Madrid? (7)
I believe the answer is:
sangria
'drink in madrid?' is the definition.
(I know that Sangria is a drink)
'celebrated artist nursing one' is the wordplay.
'celebrated' becomes 'sang' (singing might be done as part of a celebration).
'artist' becomes 'RA' (Royal Academician, member of Royal Academy of Arts).
'nursing' means one lot of letters goes inside another.
'one' becomes 'i' (Roman numeral).
'ra' enclosing 'i' is 'ria'.
'sang'+'ria'='SANGRIA'
(Other definitions for sangria that I've seen before include "Spanish drink based on red wine" , "Spanish spiced wine" , "Spanish alcoholic drink" , "Spanish drink of red wine, sugar and fruit" , "Spanish wine punch" .)