Is success story at Birmingham Weight Watchers this idle? (6)
I believe the answer is:
loiter
'this idle?' is the definition.
(thesaurus)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for loiter that I've seen before include "Mooch, hang around" , "be on stand-by?" , "Wait suspiciously" , "Hang around, lurk" , "Hang around, perhaps with intent" .)