Follow the play up to the key point (E plays the 10 which seems to have been removed).
S now agrees he hesitated, he said he was thinking about which of ♣A or K to play.
He wins the A, crosses to dummy with a diamond and leads a heart.
W wins and needing to find partner's black K, thinks that declarer could not hesitate with ♣AK, but might be thinking of ducking without the K, leads another club and declarer claims.
W thinks he's had any chance of making the right choice removed by declarer's tempo.
Now what if anything ?