A person readily welcoming me heading committee at last
I believe the answer is:
someone
'a person' is the definition.
('someone' can be a synonym of 'person')
'readily welcoming me heading committee at last' is the wordplay.
'readily' becomes 'soon' (I've seen this in other clues).
'welcoming' indicates putting letters inside (in sense of 'inviting in').
'heading' is a charade indicator (letters next to each other) (some letters go in front of or head others).
'at last' says to take the final letters.
The last letter of 'committee' is 'e'.
'soon' enclosing 'me' is 'someon'.
'someon'+'e'='SOMEONE'
(Other definitions for someone that I've seen before include "A person (maybe of importance)" , "big cheese" , "An unknown person" , "Important person" , "Unspecified human being" .)