Residential tenure means old Charlie can keep up with costly housing (9)

I believe the answer is:

occupancy

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

'residential tenure' is the definition.
'occupancy' can be an answer for 'tenure' (I've seen this before). I am not sure about the 'residential' bit.

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for occupancy that I've seen before include "The proportion of a hotel in use" , "Tenancy" , "possession" , "Tenure" , "Residence" .)

I've seen this clue in the Sydney Morning Herald.

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