Philosopher some philosopher trashed on reflection (6)
I believe the answer is:
sartre
'philosopher' is the definition.
(I've seen this before)
'some philosopher trashed on reflection' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'on reflection' shows that the letters should be reversed in order.
'ertras' is hidden in the letters of 'philosopher trashed'.
'ertras' in reverse letter order is 'SARTRE'.
(Other definitions for sartre that I've seen before include "Sooner" , "Jean-Paul ___, French existentialist, d. 1980" , "Jean-Paul -, French philosopher/author" , "Jean-Paul -, Fr. author" , "Arrest (anag) - French philosopher, d. 1980" .)