BeerBorg

Ok just to start this right. I don't know if using Cluster hops as flavor and aroma is "in style" for a APA . (since I'm not brewing for competition I only care academically) I'm drinking my Middletown Pale Ale and that "spicy" cluster has is a great taste and sets off the rye quite well.

IDK; never even seen Cluster at my LHBS. Let us know how it turns out! Here are examples of APAs from the BJCP:
Commercial Examples
Sierra Nevada Pale Ale, Stone Pale Ale, Great Lakes Burning River Pale Ale, Bear Republic XP Pale Ale, Anderson Valley Poleeko Gold Pale Ale, Deschutes Mirror Pond, Full Sail Pale Ale, Three Floyds X-Tra Pale Ale, Firestone Pale Ale, Left Hand Brewing Jackman's Pale Ale

Cluster is just fine... It's an original U.S. Hop...

One of the oldest wild hops as a matter of fact...

Was probably in APA's before they were called APA's!

Before there was a BJCP in fact...

If spicy is what you're aiming for, go for it! Esp. with rye, like you said. Should be an intense pale ale.

The Hat's First Rule of Homebrewing:

If you like the beer you made, YOU DID IT RIGHT!