Deadlock: four leave showing no emotion (7)
I believe the answer is:
impasse
'deadlock' is the definition.
('impasse' can be a synonym of 'deadlock')
'four leave showing no emotion' is the wordplay.
'four' becomes 'iv' (roman numeral).
'leave' suggests deleting specific letters.
'showing no emotion' becomes 'impassive' (I've seen this before).
'impassive' with 'iv' taken away is 'IMPASSE'.
(Other definitions for impasse that I've seen before include "cul-de-sac" , "Situation in which progress is impossible" , "nothing can be done" , "Dead end" , "Stalemate situation" .)