I am installing a claw foot tub with the trap below the finish floor. How do I connect the drain line to the trap below the tile floor?

I am installing a claw foot tub with the trap below the finish floor. How do I connect the drain line to the trap below the tile floor?
Sounds like you've run out of space and now the tub waste's too short to hook up with the trap raiser. Not to worry! Pick up compression type tailpiece extension,(see image) from a local plumbing shop and you're back in business. Good luck. Tom