Mastery of various dances, some with constant interruption (10)
I believe the answer is:
ascendancy
'mastery' is the definition.
(thesaurus)
'various dances some with constant interruption' is the wordplay.
'various' indicates an anagram.
'some' becomes 'any' (similar in meaning).
'with' is an insertion indicator.
'constant interruption' becomes 'c' (I can't explain this - if you can you should believe this answer much more).
'any' placed around 'c' is 'ancy'.
'dances' anagrammed gives 'ascend'.
'ascend'+'ancy'='ASCENDANCY'
'of' acts as a link.
(Other definitions for ascendancy that I've seen before include "Dominance" , "Condition of being dominant" , "Domination" , "Candy canes (anag.)" , "sway" .)