Philosophical concept analysed as rot, badly (6,4)
I believe the answer is:
astral body
'philosophical concept' is the definition.
(astral body matches up with the definition philosophical concept)
'analysed as rot badly' is the wordplay.
'analysed' indicates an anagram.
'as'+'rot'+'badly'='asrotbadly'
'asrotbadly' is an anagram of 'ASTRAL BODY'.
(Other definitions for astral body that I've seen before include "Spiritual counterpart of physical existence" , "(In theosophy) supposed aura representing personality - roast badly (anag)" .)