"Wonderwall" group (5)
I believe the answer is:
oasis
'wonderwall group' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for oasis that I've seen before include "British band" , "Place of refreshment" , "Florist's foam" , "Manchester band featuring the Gallagher brothers" , "Fertile area in 7?" .)