An enthusiast to get on and flourish (7)
I believe the answer is:
fanfare
'flourish' is the definition.
(I know that flourish can be written as fanfare)
'an enthusiast to get on' is the wordplay.
'an enthusiast' becomes 'fan' (fan is a kind of enthusiast).
'to get on' becomes 'fare' (I've seen this in another clue).
'fan'+'fare'='FANFARE'
'and' acts as a link.
(Other definitions for fanfare that I've seen before include "Musical flourish" , "Ceremonious sounding of trumpets" , "Flourish played at military Ceremonial" , "Short ceremonial tune for trumpets" , "Short piece of music played on brass instruments (for the Common Man?)" .)