My husband and I share an Apple ID. Is there a way to get a family subscription using one Apple ID?

You need more than one Apple ID to participate in a Family Sharing group. Think it through; what would be the point in setting up a sharing facility for a single Apple ID?

However, I would strongly urge you to have separate Apple IDs for yourself and for your husband - then the sharing group would be useful. Many of those who share Apple ID create a mess for themselves which takes some effort to untangle.

Apple actively discourages the sharing of IDs as they advise in the support document Manage and use your Apple ID: Don’t share your Apple ID with other people, even family members.

Apple Music is one of the many services Family Groups can share: With Family Sharing, you and up to five other family members can share access to amazing Apple services such as iCloud+, Apple Music, Apple TV+, Apple Fitness+, Apple News+ and Apple Arcade. Your group can also share iTunes, Apple Books and App Store purchases, and a family photo album. You can even help locate each other’s missing devices.

On this page (on the US website) Apple tells you that with Family Sharing activated The Apple Music Family Plan, which allows you to share your account with up to five people and gives each member a personal account, is just $14.99 per month.

No. The system is designed for one ID, one person. If you want to include other members of your family you can set up sharing using this ID and your wife can still, in effect, pretend to be you.