Calls for demos: and for nothing (7)
I believe the answer is:
demands
'calls for' is the definition.
('demand' can be a synonym of 'call for')
I can't explain the rest of the clue.
(Other definitions for demands that I've seen before include "Orders" , "Insistent requests" , "Requests forcefully" , "Requires" , "Asks peremptorily" .)