Have no idea on last 4 in bottom left corner:
31a Eisteddfod's finale following a Welsh line? ???L
33a In theatre at Perth you and I take the place of a feed ???OG?
22d A promoter of literary studies on bears with advanced tongue ?AH??A
23d Stew over endorsement for jerry-built shack in Jo'burg ?ON??K
(Tony, I daresay it's your turn again!)