Temporary shelter in which there's an occupant (6)
I believe the answer is:
tenant
'occupant' is the definition.
(I know that tenant is a type of occupant)
'temporary shelter in which there's an' is the wordplay.
'temporary shelter' becomes 'tent' (I've seen this before).
'in which there's' means one lot of letters goes inside another.
'tent' enclosing 'an' is 'TENANT'.
(Other definitions for tenant that I've seen before include "Resident" , "One occupying rented property" , "He pays rent for lodgings" , "Renting occupant" , "Anne Bronte's novel 'The ...... of Wildfell Hall'" .)