A supporter, and a noisy one (3)
I believe the answer is:
fan
'a supporter' is the definition.
(I know that supporter can be written as fan)
'a noisy one' is the wordplay.
'a noisy' becomes 'f'.
'one' becomes 'an' (an apple is one apple).
'f'+'an'='FAN'
'and' acts as a link.
(Other definitions for fan that I've seen before include "Cooling device for enthusiastic supporter" , "Enthusiastic admirer as of pop star" , "Cooler; enthusiast" , "Zealot" , "Cooling device for an ardent supporter" .)