I believe that she got it in spades comes from the card game of bridge where spades is considered the default suit for trump - not the American president - although any other suite can become the trump suit during bidding - if all players pass then spades becomes the default trump - I have not played this game since I was a kid many decades ago now, so consider the source. So saying somebody has it in spades is a way of saying that they are overwhelming stong. They cannot be topped.

It means to have a lot of something. I guess some card games give the highest scores to spades. Be sure to use Google, even I did just now haha