Raised plain coat and a uniform (7)
I believe the answer is:
plateau
'raised plain' is the definition.
(area of raised, flat ground)
'coat and a uniform' is the wordplay.
'coat' becomes 'plate' (plating is a kind of coating).
'and' is a charade indicator (letters next to each other).
'uniform' becomes 'u' (phonetic alphabet: alpha, bravo, charlie etc.).
'plate'+'a'+'u'='PLATEAU'
(Other definitions for plateau that I've seen before include "plane" , "State of little change after a period of activity" , "Area of livel high ground" , "Flat highland" , "Area of level high ground" .)