Last one (as always!). 13a 'Overthrow annulment'(6), -e-e-t. All these letters are confirmed. My preference is 'repeat', but 'reject' and 'defeat' could also be possible. Any thoughts appreciated.
Thanks jolan and chrise. 'Defeat' it is. My Oxford has nothing relevant under 'defeat'(n), and only gives 'annul' under 'defeat'(v). I should have checked Chambers, which actually gives 'annulment' under 'defeat'(n). We live and learn!