Will a spouse’s criminal background be investigated for a high risk public trust clearance? The SF85P requires spouses SSN. Will a spouse’s past felony offense almost 10 years impact ability to get clearance? Will it come up during the interview? Aside from that, no other issues.
It shouldn’t affect anything. They are looking at your trustworthiness and character, not your associates.
It might come up during clearance interview, since they might want to talk about anything, but I wouldn’t worry about it. You are not at fault and this doesn’t reflect on your ability to maintain a clearance.
Could they consider this something that could be used for blackmail? Felony isn’t widely known beyond close friends and family, though would come up if anyone did a background search. Could mean lose of job, reputation, friends, etc. I don’t think it is something that someone could blackmail me for, but if they ask if there is anything that could be blackmailed do I need to mention it? Will they ask about it?