An apology for a dance (6-2)
I believe the answer is:
excuse-me
This clue is a double definition.
'an apology' is the first definition.
(I've seen this before)
'dance' is the second definition.
(I've seen this before)
'for a' is the link.
(Other definitions for excuse-me that I've seen before include "Interrupting dance" , "Dance during which one changes partners" , "Polite words of interruption" , "Apology for breaking in - dance" , "Phrase to catch attention or apologise" .)