If South were in the first seat, and not vulnerable, he would likely open three clubs. In the first seat, it is twice as likely that he is preempting the opponents and not his partner. However, once partner opens there is no club preempt available.
In this example, North opens the bidding with one spade. South bids 1NT. 1NT does not promise no-trump distribution.
It just denies support for partners suit with six to nine points. It also denies four cards in any intervening suit if there is one. South will never reply three clubs to one spade unless Bergen raises or minisplinters are being used.
North then bids his second suit. With a minimum hand, South has to pick between the two. However, he has no support for either. He can bid three clubs which demands a pass from partner.
The contract: Three clubs by South
The opening lead: The ace of hearts
The play: Leading from the ace and king is one of the best leads. Partner plays the two of hearts. If East had a doubleton, he would have high-lowed partner, playing his higher card first. West not wanting to set up dummy’s hearts, switches to the queen of diamonds.
Declarer loses two hearts and two spades to make his contract.
The result: Three clubs making for +110
Note: South could have been passed in one no-trump which would have gone down a few tricks. This is better than bidding two clubs over one spade showing 10 high card points.