Philosopher, being unsure, eschews preposterous form of Russian roulette (9)
I believe the answer is:
aristotle
'philosopher' is the definition.
(Aristotle is an example)
'being unsure eschews preposterous form of russian roulette' is the wordplay.
I cannot quite see how this works, but
'being' could be 'tot' (tot is a kind of being) and 'tot' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for aristotle that I've seen before include "Greek philosopher, pupil of Plato, tutor of Alexander the Great" , "polymath" , "Totaliser for the great Greek philosopher of old" , "Ancient Athenian philosopher, pupil of Plato" , "Ancient Greek philosopher" .)