Dance with any number following garden party (7)
I believe the answer is:
hoedown
'dance' is the definition.
(I've seen this before)
'with any number following garden party' is the wordplay.
'with' becomes 'w' (abbreviation).
'any number' becomes 'n' (mathematical symbol for an unspecified number).
'following' is a charade indicator (letters next to each other).
'garden' becomes 'hoe' (to garden could mean to hoe).
'party' becomes 'do' (do is a kind of party).
'w'+'n'='wn'
'hoe'+'do'='hoedo'
'wn' after 'hoedo' is 'HOEDOWN'.
(Other definitions for hoedown that I've seen before include "Boisterous American folk dance" , "American dance gathering" , "Square dance" , "US folk dance gathering" , "Lively steps" .)