It is a guess.
However, there are two things.
For one thing, this is not a smother play. A smother play is a form of endplay in a trump contract which forces an opponent to lead a non-trump card that none of the other players have, in order to capture a protected trump honor. For example, if spades are trump and East is on lead at trick 12:
The other thing is that the correct play in the club suit, all other things being equal, is a finesse of the 10 on the first round. This would have failed on the actual hand, but it is a better percentage play than K followed by Q.