A last note turning up down under, written by a philosopher (7)
I believe the answer is:
spinoza
'philosopher' is the definition.
(I've seen this before)
'a last note turning up down under written by a' is the wordplay.
'a last note' becomes 'nips' (I can't justify this - if you can you should give a lot more credence to this answer).
'turning up' says the letters should be written in reverse.
'down under' becomes 'oz'.
'written by' means one lot of letters go next to another.
'nips' reversed gives 'spin'.
'spin'+'oz'+'a'='SPINOZA'
(Other definitions for spinoza that I've seen before include "philosophical sort" , "2 [PHILOSOPHER]" , "C17 Dutch philosopher" , "Dutch 17th-century philosopher" .)