Stalemate that is about MP on a ship (7)
I believe the answer is:
impasse
'stalemate' is the definition.
(I know that stalemate can be written as impasse)
'that is about mp on a ship' is the wordplay.
'that is' becomes 'ie' (short for Latin 'id est', 'that is').
'about' indicates putting letters inside.
'on' is a charade indicator (letters next to each other).
'ship' becomes 'SS' (prefix in ship names eg SS Great Britain).
'mp'+'a'+'ss'='mpass'
'ie' going around 'mpass' is 'IMPASSE'.
(Other definitions for impasse that I've seen before include "Standstill" , "No progress is possible in this type of situation" , "Deadlock or stand-off" , "Dead end" , "cul-de-sac" .)