Remaining proverb encapsulates emotion’s essence (7)
I believe the answer is:
staying
'remaining' is the definition.
('stay' can be a synonym of 'remain')
'proverb encapsulates emotion's essence' is the wordplay.
'proverb' becomes 'saying' (I've seen this in another clue).
'encapsulates' means one lot of letters goes inside another.
'essence' means to look at the middle letters (essence can mean the core of something).
The central letter of 'emotion' is 't'.
'saying' placed around 't' is 'STAYING'.
(Another definition for staying that I've seen is " Remaining in the same place".)