East has a standard 3♥ pre-empt.

West can see a slam or even a grand slam (if partner has A♣ and KQ♥ s)

So bids 4NT RKCB.

How does east show the void ♣ suit ?

If no agreement you could show the void as an Ace and bid 5♠s showing 2 keycards and the Q of trumps.

If you have the agreement on how to show voids.

Responder's Bids	Meaning
5NT	An even # of key cards and a void somewhere.
6	An odd # of key cards and: A club void if clubs aren't trumps, or A void in any other suit if clubs are trumps
6	An odd # of key cards and: A diamond void if hearts or spades are trumps, or A void in hearts or spades, if diamonds are trumps
6	An odd # of key cards and: A heart void if spades are trumps, or A spade void if hearts are trumps

So in this case 6♣ would show one key card and a void in ♣ s.

In both cases West can bid 6♥ s.