Dance round after smack (5)
I believe the answer is:
tango
'dance' is the definition.
(tango is a type of dance)
'round after smack' is the wordplay.
'round' becomes 'o' (o is a circular letter).
'after' says to put letters next to each other.
'smack' becomes 'tang' (synonyms).
'o' put after 'tang' is 'TANGO'.
(Other definitions for tango that I've seen before include "Ballroom dance (for two?)" , "Colourful dance from Argentina" , "Rhythmic movement" , "Dance; T (radio comms.)" , "musical piece" .)