The setter is no longer cool, coming to standstill (7)
I believe the answer is:
impasse
'standstill' is the definition.
(I've seen this before)
'the setter is no longer cool coming' is the wordplay.
'the setter is' becomes 'im' (the setter is the person who set the crossword).
'no longer cool coming' becomes 'passe' (I am not sure about this - if you are sure you should believe this answer much more).
'im'+'passe'='IMPASSE'
'to' is the link.
Can you help me to learn more?
(Other definitions for impasse that I've seen before include "No progress is possible in this type of situation" , "'Deadlock, stalemate (7)'" , "Inescapable perdicament, dilemma" , "Stalling of negotiations" , "Dead end" .)