Number given to worker who lives in another's house? (6)
I believe the answer is:
tenant
'who lives in another's house?' is the definition.
(tenants rent property)
'number given to worker' is the wordplay.
'number' becomes 'ten' (ten is a kind of number).
'given to' means one lot of letters go next to another.
'worker' becomes 'ant' (worker is a type of ant).
'ten'+'ant'='TENANT'
(Other definitions for tenant that I've seen before include "He pays rent for lodgings" , "Rent payer" , "he or she rents" , "One renting property" , "One who pays rent" .)