Here's what I did.
Wait til they're tired, to start with, and leash.
Say "paw", touch their paw, click and treat. (No clippers in sight)
Do this over and over, just touching, clicking, treating. WHen they let you, then touch for longer. Eventually holding.
Then it was touch a nail, click, treat. Repeatedly.
Then got the clipper out, click, treat.
Touch paw with clipper, click, treat. Repeatedly.
Touch nail with clipper, click treat...
(yes this takes awhile. It is worth it. Do this til he is calm about it)
THEN
Clip a TINY bit off one nail, and be super fast to click and treat a high value treat.
Do this with each nail. TINY bits, you do NOT want to quick him at his point or you're screwed.
Praise, be done, play. Maybe do one foot, or one nail, per day with this method until he is desensitized.