Feeling life, say, or time is overwhelming one (9)
I believe the answer is:
sentience
'feeling' is the definition.
(I've seen this before)
'life say or time is overwhelming one' is the wordplay.
'life say or time' becomes 'sentence' (someone may be given life as a prison sentence).
'is overwhelming' is an insertion indicator.
'one' becomes 'I' (Roman numeral).
'sentence' enclosing 'i' is 'SENTIENCE'.
(Other definitions for sentience that I've seen before include "Ability to feel or perceive" , "Consciousness -- ten nieces (anag)" , "Ability to feel things" , "mind" , "awareness" .)