I am getting an error:
gpg: no default secret key: No secret key
gpg: [stdin]: clearsign failed: No secret key
My secret keys are available to GPG.
It might be difference between gpg1 and gpg2. The secret keys are stored in different ways. You may have both of them.
Try
which gpg gpg2
If you do have both, run:
gpg2 --list-secret
gpg --list-secret
You maybe able to tell that one works, another does not.