Artist in East End district, one using a series of colours (7)
I believe the answer is:
rainbow
'one using a series of colours' is the definition.
'artist in east end district' is the wordplay.
'artist' becomes 'ra' (Royal Academician, member of Royal Academy of Arts).
'east end district' becomes 'bow' (area of East London).
'ra'+'in'+'bow'='RAINBOW'
(Other definitions for rainbow that I've seen before include "-- Coalition; -- trout" , "Whole range of colours" , "colours in the heavens" , "Phenomenon produced by light passing through water droplets" , "'I can sing a - - ' (song)" .)