I am stupid fellow, grabbing pawn -- game's ending in stalemate (7)
I believe the answer is:
impasse
'stalemate' is the definition.
('impasse' can be a synonym of 'stalemate')
'i am stupid fellow grabbing pawn game's ending' is the wordplay.
'i am' becomes 'im'.
'stupid fellow' becomes 'ass' (I've seen this before).
'grabbing' indicates putting letters inside.
'pawn' becomes 'p'.
'ending' says to take the final letters.
The final letter of 'game' is 'e'.
'im'+'ass'='imass'
'imass' placed around 'p' is 'impass'.
'impass'+'e'='IMPASSE'
'in' is the link.
(Other definitions for impasse that I've seen before include "No progress is possible in this type of situation" , "I permit no further progress" , "There's no way past it" , "failure to progress" , "Unpromising situation" .)