chalked his soles

[Sukhomvit]

Quoted from Out of Africa by I. Dinensen

"He was a very good judge of men, with no illusions about them and no spite. Out of a kind of devilry, he was most charming to the people of whom he had the poorest opinion. When he really chalked his soles for the job he was an inimitable buffoon. But to be a wit in the manner of Congreve and Wycherley en plein vingtième siècle takes a few more qualities than Congreve or Wycherley themselves had got in them: a glow, grandezza, the wild hope."

I do not understand underlined words. I guess it is something related to clown but not sure. Please kindly help me out. Thanks.

 

[Tdol]

I have never heard the expression and can't find it in my dictionaries. I would guess that it means when he really made an effort to do it.

 

[Sukhomvit]

I have never heard the expression and can't find it in my dictionaries. I would guess that it means when he really made an effort to do it.

Dear Tdol,
To give me a hint on your guess, please tell me what do you mean by saying "to do it"?
I am still not clearly understand the sentence: "Out of a kind of devilry, he was most charming to the people of whom he had the poorest opinion." May I read it as: "Because of a cruel fun, he is focusing mainly on the people of whom he had the poorest opinion"?

 

[Tdol]

When he tried to be a real buffoon, he managed to do it very well. However, his fun was not cruel- he showed no spite to those he disliked. His mockery was not an attack.