Meeting original sinner, not heartless (5)
I believe the answer is:
event
'meeting' is the definition.
(meeting is a type of event)
'original sinner not heartless' is the wordplay.
'original sinner' becomes 'eve' (I've seen this in another clue).
'heartless' says to hollow out the word (remove centre letters).
'not' with its middle taken out is 'nt'.
'eve'+'nt'='EVENT'
(Other definitions for event that I've seen before include "A notable occurrence or happening" , "Affair" , "match" , "Something taking place" , "Incident, occurrence" .)