Coloured single old penny with bit of tallow (5)
I believe the answer is:
toned
'coloured' is the definition.
(toning is a kind of colouring)
'single old penny with bit of tallow' is the wordplay.
'single' becomes 'one' (a single thing - only one).
'old penny' becomes 'd' (pre-decimal abbreviation for penny).
'with' is a charade indicator (letters next to each other).
'bit of' indicates taking the first letters.
The initial letter of 'tallow' is 't'.
'one'+'d'='oned'
'oned' put after 't' is 'TONED'.
(Other definitions for toned that I've seen before include "Slightly tinted; firm-muscled" , "pitched just right" , "Noted (anag.)" , "went well" , "Muscular" .)