Philosopher in audible whisper? (7)
I believe the answer is:
russell
'philosopher' is the definition.
(Bertrand Russell)
'audible whisper?' is the wordplay.
'audible' indicates a 'sounds like' (homophone) clue.
'whisper?' becomes 'rustle' (synonyms).
'rustle' sounds like 'RUSSELL'.
'in' acts as a link.
(Other definitions for russell that I've seen before include "Ken -, Eng. film director (Women in Love)" , "Jack -, type of terrier" , "actress (Rosalind or Jane)" , "Jane -, US actress" , "Brand" .)