Yours truly is out in blind alley (7)
I believe the answer is:
impasse
'blind alley' is the definition.
(synonyms)
'yours truly is out' is the wordplay.
'yours truly is' becomes 'im'.
'out' becomes 'passe' (I've seen this before).
'im'+'passe'='IMPASSE'
'in' acts as a link.
(Other definitions for impasse that I've seen before include "'Deadlock, no progress can be made (7)'" , "Stalling of negotiations" , "failure to progress" , "nothing can be done" , "hopeless situation?" .)