Crossword Genius

One's responsible for housing issue after the folks have departed (9)

Ross

I believe the answer is:

orphanage

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

'departed' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.

'one's responsible for housing issue after the folks' is the wordplay.
I cannot quite understand how this works, but
'one' could be 'an' (an apple is one apple) and 'an' is found in the answer.
This explanation may well be incorrect...

'have' acts as a link.

Can you help me to learn more?

(Other definitions for orphanage that I've seen before include "Institution for parentless or abandoned children" , "Children's home" , "home for kids" , "Parentless children's institution" , "left children here?" .)

I've seen this clue in The Independent.
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