Philosophy of bare existence? (6)
I believe the answer is:
nudism
This clue is a double definition.
'philosophy' is the first definition.
(nudism is a kind of philosophy)
'bare existence?' is the second definition.
(I've seen this in another clue)
'of' acts as a link.
(Other definitions for nudism that I've seen before include "Mind us (anag)" , "The practice of wearing no clothes" , "Having nothing on" , "early practice in Eden" , "Pursuit of a naturist" .)