Supporter, blonde, heard trumpet call (7)
I believe the answer is:
fanfare
'trumpet call' is the definition.
(I've seen this before)
'supporter blonde heard' is the wordplay.
'supporter' becomes 'fan' (fan is a kind of supporter).
'blonde' becomes 'fair' (similar in meaning).
'heard' indicates a 'sounds like' (homophone) clue.
'fair' sounds like 'fare'.
'fan'+'fare'='FANFARE'
(Other definitions for fanfare that I've seen before include "Brass flourish" , "Flourish played at military Ceremonial" , "Flourish of trumpets" , "elaborate ceremony" , "Trumpet call" .)