Appropriate by a rostrum to acknowledge applause (4,1,3)
I believe the answer is:
take a bow
But I can't explain it at all! Could you help me understand?
(Other definitions for take a bow that I've seen before include "Acknowledge your audience" , "Acknowledge applause with physical posture" , "Violinist's lesson one" , "Before playing, cellist must" , "to acknowledge admirers" .)