Tenant with lower entrance on the outside (6)

I believe the answer is:

lessee

I'm a little stuck... Click here to teach me more about this clue!

'tenant' is the definition.
(I know that lessee is a type of tenant)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for lessee that I've seen before include "One renting a property" , "The one taking out lease" , "Who pays the rent" , "Person who rents" , "Tenant who holds a lease" .)

I've seen this clue in The Sun and The Times.

Want a hint initially instead of a full solution? Install my app