Beat topping lead in ballroom dance (5)
I believe the answer is:
tango
'ballroom dance' is the definition.
(tango is a kind of ballroom dance)
'beat topping lead' is the wordplay.
'beat' becomes 'tan' (I've seen this before).
'topping' means one lot of letters go next to another.
'lead' becomes 'go' ('go' can be a synonym of 'lead').
'tan'+'go'='TANGO'
'in' acts as a link.
(Other definitions for tango that I've seen before include "Colourful dance from Argentina" , "Tonga (anag.)" , "one followed by uniform" , "something seen in ballroom?" , "Dance; T (radio comms.)" .)