Fancy dress ball prevailed upon to include square dancing (10)
I believe the answer is:
masquerade
'fancy dress' is the definition.
(synonyms)
'prevailed upon to include square dancing' is the wordplay.
'prevailed upon' becomes 'made' (to prevail upon is to make or persuade).
'to include' is an insertion indicator.
'dancing' is an anagram indicator.
'square' is an anagram of 'squera'.
'made' placed around 'squera' is 'MASQUERADE'.
'ball' 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 masquerade that I've seen before include "Pretence - masked ball" , "Adam's queer? (anag)" , "Pretend to be someone one is not" , "Deception" , "False show - disguise oneself" .)