Jack and I have a dance (4)
I believe the answer is:
jive
'a dance' is the definition.
(I know that jive is a type of dance)
'jack and i have' is the wordplay.
'jack' becomes 'J' (playing card abbreviation).
'and' is a charade indicator (letters next to each other).
'i have' becomes 'I've' (contraction of 'I have').
'j'+'ive'='JIVE'
(Other definitions for jive that I've seen before include "Fast dancing style" , "Style of fast dance music" , "Jerky, jazz dance of the 1950s" , "Nineteen fifties dance style" , "Lively dance" .)