Fly round circle in dance (5)
I believe the answer is:
tango
'dance' is the definition.
(tango is a type of dance)
'fly round circle' is the wordplay.
'fly' becomes 'gnat' (type of insect).
'round' shows that the letters should be reversed in order.
'circle' becomes 'O' (O is a circle).
'gnat' written backwards gives 'tang'.
'tang'+'o'='TANGO'
'in' acts as a link.
(Other definitions for tango that I've seen before include "uniform to follow" , "Dance of South American origin" , "Argentinian dance form" , "Activity requiring two to" , "reputedly takes two" .)