Whistleblower perhaps accrues nuts (7)
I believe the answer is:
accuser
'whistleblower perhaps' is the definition.
(I know that whistleblower is a type of accuser)
'accrues nuts' is the wordplay.
'nuts' indicates anagramming the letters (nuts can mean crazy).
'accrues' with letters rearranged gives 'ACCUSER'.
(Other definitions for accuser that I've seen before include "one to prosecute" , "I may charge" , "Denouncer" , "Zola, for example" , "Plaintiff" .)