Okay! For starters: your wife's clit sounds like every clit in the universe. They are finicky, persnickety little monsters capable of great pleasure and great discomfort. They, not unlike the women they are attached to, require nuanced care and careful attention.
First and foremost: does she own any toys? It is super important to be in touch with your own body and to feel what it's like to bring yourself to orgasm manually. BUT, if we're thinking of this like a distance race (we are, apparently) practice and exercise will make things easier in the long run. Something that vibrates will make this happen quickly. If you and your wife have never owned a toy before, I'd recommend starting with something small and un-intimidating at first, like a classic bullet. This can be used on her own or together and is a great way to warm up.
If she enjoys the sensation of the bullet (it would be hard to imagine not enjoying that), a traditional, rabbit-style vibrator is a great investment for solo workouts. There is a reason people went banana-boats for these things when they first arrived on the scene, they are orgasm factories.
So there's the physical stuff. But the second, and probably most important component: nothing dries a pussy up faster than pressure. Well, not PHYSICAL pressure, you guys. Mental and emotional pressure. Work with me here. She is probably FREAKING OUT that you think you're not doing a good job, or that some part of her anatomy is broken, wondering why she is taking so long to come. When these things enter our brains during sex, coming like a freight train comes off the table. Our brains and our vaginas are more interconnected than you would ever care to imagine. So, what I'm saying here is, be sure to let her know that you are so focused on this issue because you want her to feel good! If you can both feel like this is a fun thing to work on together, and not something to be stressed out over, the moans will start coming much faster, I promise.
One final thing: we don't always like to say it, but sometimes we're thinking, "Ouch, what you are doing fucking really hurts right now." Oftentimes, we don't say it because we don't want to take either of us out of the moment. Take cues from her physicality. If she is squirming away from the pressure you're putting on her clit, relax it just a bit. When she starts leaning into you, you're doing it right! And lastly, when she says, "Oh my god, don't stop," DO NOT STOP. Do not go faster. Do not go slower. Do not take this moment to try some new fun thing you've been thinking of. Do exactly what you are doing for the next twenty or four or eleven seconds. Do EXACTLY what you are doing until she loses her marbles and wakes the neighbors.
I hope you've all enjoyed this (not so) short PSA on behalf of the clits of planet Earth.