Blasted a colour, say (4)
I believe the answer is:
blew
'blasted' is the definition.
(I've seen this in another clue)
'a colour say' is the wordplay.
'a colour' becomes 'blue' (blue is a colour).
'say' shows a homophone (sound like).
'blue' is a homophone of 'BLEW'.
(Other definitions for blew that I've seen before include "Played (a horn)" , "Bungled (an opportunity)" , "Tooted" , "Breathed hard" , "Sounded (a whistle)" .)