What a has-been may say is a deadlock? (7)
I believe the answer is:
impasse
'deadlock?' is the definition.
(I know that deadlock can be written as impasse)
I cannot understand how the remainder of the clue works.
(Other definitions for impasse that I've seen before include "nothing can be done" , "Dead end" , "hopeless situation?" , "Unpromising situation" , "deadlock results" .)