Colours as well in darts game (8)
I believe the answer is:
standard
'colours' is the definition.
(I've seen this before)
'as well in darts game' is the wordplay.
'as well' becomes 'and' (I've seen this in other clues).
'in' indicates putting letters inside.
'game' indicates anagramming the letters (a game or puzzle of the letters).
'darts' is an anagram of 'stard'.
'and' going inside 'stard' is 'STANDARD'.
(Other definitions for standard that I've seen before include "Ordinary Level?" , "Flag - accepted level" , "Normal - colours" , "Reference point, benchmark" , "Stock - basic - flag" .)