Feeling ecstatic about connection with Newton (8)
I believe the answer is:
sentient
'feeling' is the definition.
(synonyms)
'ecstatic about connection with newton' is the wordplay.
'ecstatic' becomes 'sent' (send can mean to stimulate or excite).
'about' means one lot of letters goes inside another.
'connection' becomes 'tie' (tie is a kind of connection).
'with' is a charade indicator (letters next to each other).
'newton' becomes 'N' (symbol for the scientific unit of force).
'tie' put after 'n' is 'ntie'.
'sent' going around 'ntie' is 'SENTIENT'.
(Other definitions for sentient that I've seen before include "Capable of feeling things as in tenets" , "Conscious - aware" , "Feeling, conscious" , "Able to perceive/feel" , "having power of perception" .)