The Parisian, back in unusual hideout: a hospital in Nice (5-4)

'a hospital in nice' is the definition.
I know nothing about this answer so I can't judge whether this works.

'the parisian back in unusual hideout' is the wordplay.
'the parisian' becomes 'le' (definite article in French).
'back' says the letters should be written backwards.
'in' means one lot of letters goes inside another.
'unusual' indicates an anagram.
'le' backwards is 'el'.
'hideout' is an anagram of 'hotdieu'.
'el' put within 'hotdieu' is 'HOTEL-DIEU'.

Can you help me to learn more?