Verify surprisingly tame end of game (9)
I believe the answer is:
checkmate
'end of game' is the definition.
(I've seen this before)
'verify surprisingly tame' is the wordplay.
'verify' becomes 'check' (checking is a kind of verifying).
'surprisingly' indicates an anagram.
'tame' anagrammed gives 'mate'.
'check'+'mate'='CHECKMATE'
(Other definitions for checkmate that I've seen before include "The final killer move in chess" , "Winning call on board" , "Winning chess position" , "Declaration of chess victory" , "Last call in chess" .)