Harmonious plan to brighten up the home perhaps (6,6)
I believe the answer is:
colour scheme
'brighten up the home perhaps' is the definition.
I can't tell whether this defines the answer.
'harmonious plan' is the wordplay.
'harmonious' becomes 'colour' (I can't justify this - if you can you should believe this answer much more).
'plan' becomes 'scheme' (scheme is a kind of plan).
'colour'+'scheme'='COLOUR SCHEME'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for colour scheme that I've seen before include "dictating arrangements for the flat, say" , "Arrangement or combination of tones and hues" , "Interior decoration plan" .)