Other forms: clienteles
Your customers are your clientele. If you own a pet food store, your clientele might be two-footed and four-pawed.
The noun clientele is often preceded by an adjective to describe the exact type of customer. Little boutiques in upscale neighborhoods probably cater to an exclusive clientele, while the kids' hair salon might have Barney on video to keep the young clientele motionless in their chairs. Regardless of business type, you are always trying to please the clientele.