Unpaired dance card (7)
I believe the answer is:
oddball
'card' is the definition.
The answer and definition can be both people as well as being singular nouns.
Maybe there's a link between them I don't understand?
'unpaired dance' is the wordplay.
'unpaired' becomes 'odd' (synonyms).
'dance' becomes 'ball' (ball is a kind of dance).
'odd'+'ball'='ODDBALL'
Can you help me to learn more?
(Other definitions for oddball that I've seen before include "Crank" , "Eccentric character" , "Strange, bizarre" , "Eccentric person (colloq.)" , "Strange person (colloq.)" .)