Dance held by Swiss ambassador (5)
I believe the answer is:
samba
'dance' is the definition.
(Brazilian dance)
'held by swiss ambassador' is the wordplay.
'held by' indicates the answer is hidden within the clue.
'SAMBA' can be found hidden inside 'swiss ambassador'.
(Other definitions for samba that I've seen before include "moves from Brazil" , "Latin dance" , "Lively ballroom dance from Brazil" , "Dance music" , "Brazilian dance" .)