Minor eminence not well dressed in white (7)
I believe the answer is:
hillock
'minor eminence' is the definition.
(small hill)
'not well dressed in white' is the wordplay.
'not well' becomes 'ill' ('ill' is the opposite to 'well').
'dressed in' is an insertion indicator (inserted letters are dressed in others).
'white' becomes 'hock' (type of white wine).
'ill' inserted into 'hock' is 'HILLOCK'.
(Other definitions for hillock that I've seen before include "Barrow" , "Mound, knoll" , "elevated ground" , "Rising" , "it requires little effort to get up" .)