Dance around becomingly when it's essential to assert supremacy (9)
I believe the answer is:
dominance
'supremacy' is the definition.
(I've seen this before)
'dance around becomingly when it's essential to' is the wordplay.
'around' means one lot of letters goes inside another.
'becomingly' becomes 'mi' (I can't explain this - if you can you should give a lot more credence to this answer).
'when' becomes 'on' (I've seen this in other clues).
'it's essential to' indicates putting letters inside (inserted letters contained by essential to others).
'mi' put inside 'on' is 'omin'.
'dance' enclosing 'omin' is 'DOMINANCE'.
'assert' is the link.
I am not very happy about this link. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for dominance that I've seen before include "top position" , "Control - ascendency" , "Mastery" , "Supremacy" , "Influence (over others)" .)