Presume dancing is best (7)
I believe the answer is:
supreme
'is best' is the definition.
(I've seen this before)
'presume dancing' is the wordplay.
'dancing' indicates anagramming the letters.
'presume' is an anagram of 'SUPREME'.
(Other definitions for supreme that I've seen before include "Sovereign" , "over the top" , "Best of all" , "Cardinal, foremost" , "creamy dish of chicken perhaps" .)