When you have him out touch his feet, even if he huffs and pulls them back. Keep going. The more you can get him used to touching his feet the better it is for everyone.
Some people use a colander or tennis racket so their nails poke through and you can cut them easier.
And give a treat, I do a treat for each foot I can get done.
I can now get all feet done in one evening majority the time.
Its really about trying to find a way both of you are comfortable.
You could try holding him to your chest and catch little feet wait for the calm moment and then clip.