Feeling thrilled about new relationship (8)
I believe the answer is:
sentient
'feeling' is the definition.
(synonyms)
'thrilled about new relationship' is the wordplay.
'thrilled' becomes 'sent' (I've seen this before).
'about' is an insertion indicator.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'relationship' becomes 'tie' (tie is a kind of relationship).
'n'+'tie'='ntie'
'sent' going around 'ntie' is 'SENTIENT'.
(Other definitions for sentient that I've seen before include "Able to perceive/feel" , "Capable of feeling and perceiving things" , "having power of perception" , "Capable of feeling things as in tenets" , "Having feelings" .)