Barman in a club dancing on piano (8)
I believe the answer is:
publican
'barman' is the definition.
(I know that publican is a type of barman)
'in a club dancing on piano' is the wordplay.
'dancing' indicates an anagram.
'on' says to put letters next to each other.
'piano' becomes 'p' (musical abbreviation).
'in'+'a'+'club'='inaclub'
'inaclub' is an anagram of 'ublican'.
'ublican' put after 'p' is 'PUBLICAN'.
(Other definitions for publican that I've seen before include "Taverner" , "local man" , "Bar owner" , "Landlord or landlady" , "Old tax-collector" .)