Listen twice for approval from audience (4,4)
I believe the answer is:
hear hear
'approval from audience' is the definition.
(words of encouragement to a speaker)
'listen twice' is the wordplay.
'listen' becomes 'hear' (I've seen this in another clue).
'twice' shows that letters should be duplicated.
'hear' duplicated is 'HEAR HEAR'.
'for' is the link.
(Other definitions for hear hear that I've seen before include "express approval" , "Agreed" , "Listen, listen - it's approval" , "Jolly good!" , "Well said!" .)