The Corrs, a fantastic band (9)
I believe the answer is:
orchestra
'band' is the definition.
(musical band)
'the corrs a fantastic' is the wordplay.
'fantastic' indicates an anagram.
'the'+'corrs'+'a'='thecorrsa'
'thecorrsa' with letters rearranged gives 'ORCHESTRA'.
(Other definitions for orchestra that I've seen before include "Group of musicians found on cart-horse" , "Musical ensemble" , "many players" , "Ensemble of players" , "Theatre area for musicians" .)