Clue: Sumptuous place on the Nile needs nothing altered before one starts to advertise new tenancy (9)
Answer: LUXURIANT
Explanation: Definition: Sumptuous
A charade of LUXUR, which is LUXOR ('place on the Nile') with the O changed ('nothing altered'; only the answer indicates that the change is to a U) plus I ('one') plus A N T ('starts to **A**dvertise **N**ew **T**enancy')