What is the easiest way to farm Nazar?

I need a Nazar. It is the last ingredient for the Ankh Shield I need and it seems difficult to receive.

Is there a good way to get it?

Since you have all the other ingredients I surmise that you are in hardmode. I am not yet in hardmode, but I have farmed a nazar. Since the enemies in harmode are much, well, harder I would suggest farming it in a new world that is not in hardmode yet. It takes some time to drop, but the easiest enemy that drops it are the Cursed Skulls in the non-hardmode dungeon.

I would suggest creating a new world, defeating Skeletron, and finding a place in the dungeon where Cursed Skulls spawn. With hardmode gear you shouldn't have too much trouble hanging around waiting for a drop. I used the bee armor with imps, and the vilethorn, but there are probably better loadouts if you have hardmode equipment available. It took me several real time hours though, as you have to get a bit lucky. Using a water candle or battle potion will increase the spawn rate, if you feel that you can handle it.

Good luck.

This is probably a very late comment, but on mobile, I am currently using full chlorophyte armour + water candle in hand + water candle nearby + battle potion for farming a Nazar. Oh, and I also used a new world's dungeon so that I didn't get destroyed by hardmode enemies.

I closed myself in a box, with a 2-block thick roof, with a 2x1 gap in the roof. (having a door is optional, just remember to use a block as a barricade) -Grapple yourself into the 2x1 gap and the chlorophyte leaf (from full set of chlorophyte armour, and make sure the leaf is poking out of the box) will kill the monsters for you.

I've gotten 2 Nazars and 50+ golden keys from being afk. Dark Casters tend to tp into the box, but they'll teleport out later and be killed by the leaf. You can use minions with the leaf, too.

The Nazar is by far the hardest Ankh Charm item I tried to get. Every item I got in a few minutes, but the Nazar took actual farming.