Cocktail dress inspiring painting? (7)
I believe the answer is:
martini
'cocktail' is the definition.
(I know that Martini is a type of cocktail)
'dress inspiring painting?' is the wordplay.
'dress' becomes 'mini' (mini dress).
'inspiring' means one lot of letters goes inside another.
'painting?' becomes 'art' (painting is an art).
'mini' placed around 'art' is 'MARTINI'.
(Other definitions for martini that I've seen before include "In glass, one's dry" , "alcoholic drink" , "Type of Italian vermouth" , "tipple" , "Cocktail made with gin or vodka and vermouth" .)