"In spades" ? From card games e.g bridge.The suits of cards are ranked: spades, hearts, diamonds, clubs, spades being the highest. So, in bridge, a contract 'in spades' (a promise to take a given number of tricks when spades are trumps) scores more than a contract in clubs. ( I simplify: bridge has more complexity than that suggests, but the example is true)
So 'in spades' indicates being in an exceptionally good position, better than average, better than at first appears ,since a card in spades with the same face value as a card in diamonds or clubs is worth more than those.