Bertrand —, philosopher (7)
I believe the answer is:
russell
I believe this is a double definition.
'bertrand' is the first definition.
'philosopher' is the second definition.
(Bertrand Russell)
(Other definitions for russell that I've seen before include "Brand" , "actress (Rosalind or Jane)" , "...another one [PHILOSOPHER]" , "Jane -, US actress" , "group of universities" .)