Envoys schedule time with Liberal from the South (7)
I believe the answer is:
legates
'envoys' is the definition.
(legate is a kind of envoy)
'schedule time with liberal from the south' is the wordplay.
'schedule' becomes 'set'.
'time' becomes 'age' (an age is a period of time).
'with' is a charade indicator (letters next to each other).
'liberal' becomes 'l' (abbreviation).
'from the south' is a reversal indicator (in a down clue, letters go up).
'set'+'age'+'l'='setagel'
'setagel' back-to-front is 'LEGATES'.
(Other definitions for legates that I've seen before include "representatives" , "Pope's envoys" .)