Heavenly arch for artist in East London (7)
I believe the answer is:
rainbow
'heavenly arch' is the definition.
'rainbow' can be an answer for 'arch' (I have seen 'Coloured arch ' mean 'rainbow' so perhaps 'arch' could also mean 'rainbow'). I'm not sure about the 'heavenly' bit.
'artist in east london' is the wordplay.
'artist' becomes 'RA' (Royal Academician, member of Royal Academy of Arts).
'east london' becomes 'bow' (area of east London).
'ra'+'in'+'bow'='RAINBOW'
'for' acts as a link.
Can you help me to learn more?
(Other definitions for rainbow that I've seen before include "Arc of colored light in the sky" , "Arc caused by refraction of the sun's rays (7" , "Refracted light in sky" , "There's a pot of gold at the end of it" , "Water-colour production" .)