Agent in meeting to introduce short sad song (8)
I believe the answer is:
delegate
'agent' is the definition.
(thesaurus)
'in meeting to introduce short sad song' is the wordplay.
'in meeting' becomes 'date' (date is a kind of meeting. I am not sure about the 'in' bit.).
'to introduce' is an insertion indicator (to introduce to can mean to insert or include).
'short' means to remove the last letter.
'sad song' becomes 'elegy' (I've seen this in another clue).
'elegy' with its final letter taken off is 'eleg'.
'date' placed around 'eleg' is 'DELEGATE'.
Can you help me to learn more?
(Other definitions for delegate that I've seen before include "One represents" , "Give power to someone else" , "Person who represents others as at meeting" , "Representative sent to meeting" , "Envoy" .)