Weary end to game after squash rally (8)
I believe the answer is:
jamboree
'rally' is the definition.
(jamboree can mean a gathering or rally)
'weary end to game after squash' is the wordplay.
'weary' becomes 'bore' (as a verb).
'end to' says to take the final letters.
'after' means one lot of letters go next to another.
'squash' becomes 'jam' (jam can mean to squash or bash).
The last letter of 'game' is 'e'.
'bore'+'e'='boree'
'boree' after 'jam' is 'JAMBOREE'.
(Other definitions for jamboree that I've seen before include "Large scout rally" , "'Gala get-together, of scouts say (8)'" , "Party - gathering of Scouts" , "Scout or Guide rally" , "Scout gathering; big party" .)