Dance with boy attending ball? Not half! (5)
I believe the answer is:
samba
'dance' is the definition.
(sambaing is a kind of dancing)
'boy attending ball? not half' is the wordplay.
'boy' becomes 'sam' (I've seen this before**).
'attending' says to put letters next to each other.
'not half' indicates taking half.
'ball' with half the letters taken is 'ba'.
'sam'+'ba'='SAMBA'
'with' acts as a link.
(Other definitions for samba that I've seen before include "Latin dance" , "Dance music" , "Lively ballroom dance from Brazil" , "it was launched in Brazil" , "Dance, originally from Brazil" .)