Tie game: would that be a letdown in medieval times? (10)
I believe the answer is:
drawbridge
'would that be a letdown in medieval times?' is the definition.
(drawbridges were let down in medieval times)
'tie game' is the wordplay.
'tie' becomes 'draw' (synonyms).
'game' becomes 'bridge' (card game).
'draw'+'bridge'='DRAWBRIDGE'
(Other definitions for drawbridge that I've seen before include "this may have been deployed in defence" , "It has its ups and downs" , "It spans a moat" , "Keep attachment" , "Castle defence" .)