Knees-up after a song and dance (3)
I believe the answer is:
ado
'song and dance' is the definition.
(both can mean a commotion or fuss)
'knees-up after a' is the wordplay.
'knees up' becomes 'do' (I can't explain this - if you can you should give a lot more credence to this answer).
'after' means one lot of letters go next to another.
'do' put after 'a' is 'ADO'.
Can you help me to learn more?
(Other definitions for ado that I've seen before include "Song and dance" , "Fuss, difficulty" , "Rapid bustling commotion" , "stir" , "excitement" .)