Stunning - but not working! (8)
I believe the answer is:
striking
I believe this clue is a double definition.
'stunning' is the first definition.
(I've seen this in another clue)
'not working' is the second definition.
(I've seen this before)
'but' acts as a link.
(Other definitions for striking that I've seen before include "going like the clappers?" , "Prominent" , "stopping work" , "Conspicuous" , "Signal" .)