Walls of temple retaining a cheerful colour (5)
I believe the answer is:
taupe
'colour' is the definition.
(I know that taupe is a type of brown)
'walls of temple retaining a cheerful' is the wordplay.
'walls of' says to hollow out the word (remove centre letters) (only the edge letters remain).
'retaining' indicates putting letters inside (inserted letters are held or retained).
'cheerful' becomes 'up' (I've seen this in other clues).
'temple' with its centre removed is 'te'.
'a'+'up'='aup'
'te' enclosing 'aup' is 'TAUPE'.
(Other definitions for taupe that I've seen before include "colour of moleskin" , "shade" , "Greyish brown" , "Fifty Shades of Grey must include this" , "Grey tinged with brown" .)