Turn over waffle (2,2)
I believe the answer is:
go on
'waffle' is the definition.
(thesaurus)
'turn over' is the wordplay.
'turn' becomes 'go' (a person's move in a board game).
'over' becomes 'on' (physically on top of).
'go'+'on'='GO ON'
(Other definitions for go on that I've seen before include "Hired thug" , "Stupid person or ruffian - go on with it" , "Peter Sellers or Spike Milligan, say" , "Peter Sellers, Spike Milligan or Harry Secombe" , "Foolish person - thug (US)" .)