Lower entrance on the outside for tenant (6)
I believe the answer is:
lessee
'for tenant' is the definition.
(lessee is a kind of tenant)
'lower entrance on the outside' is the wordplay.
'lower' becomes 'less' (synonyms).
'on the outside' says to hollow out the word (remove centre letters).
'entrance' with its centre taken out is 'ee'.
'less'+'ee'='LESSEE'
(Other definitions for lessee that I've seen before include "One granted temporary use of property" , "Hirer of property" , "One holds a lease" , "Contractor" , "I have to deal with letter" .)