Old people's home? Not exactly (4)

I believe the answer is:

inca

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

'old people's home? not exactly' is the definition.
I can't tell whether this definition defines the answer.

'home? not exactly' is the wordplay.
'home?' becomes 'in' (to be in is to be (at) home).
'not exactly' becomes 'ca' (circa).
'in'+'ca'='INCA'

Can you help me to learn more?

(Other definitions for inca that I've seen before include "Atahualpa was" , "Very old Peruvian (4)." , "who lived in S America" , "Member of ancient Peruvian tribe" , "Former emperor" .)

I've seen this clue in The Times.

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