Found:

Pseudo-cleft

SYNTAX: in the pseudo-cleft construction, like the cleft construction, some part X of a sentence is focussed. EXAMPLE: (ii) is a pseudo-cleft version of (i). The focussed part X (a herring) is associated with a free relative clause in a copula construction:

(i)  John ate a herring
(ii) [What John ate e] was a herring