What does 'crack' here mean?

He wanted a crack at Will Harris.

(He is a policeman, and Will Harris is a suspect, and he is going to interrogate him.)

Hi, Antonia!
"to have a crack at something" means "to get a chance to do something"
So in your context, It's something like "he wanted a chance to interrogate him, talk with him, see what he could learn"
I think both "a crack at" and "a shot at" are both shooting terms. The policeman had Harris in his sights and wanted to shoot him down.

In other words, the policeman really wanted to interview Harris, because he suspected him and felt he could get information from him.

compare: "I'd like a crack at bunjee jumping" = I've never been bunjee jumping, but I'd like to try it"
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Thank you pieanne;
I see you are into ticks now, good luck!
 abbie1948's reply was promoted to an answer.
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Thanks abbie