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 cannot judge whether it can be defined by this definition.

'the parisian back in unusual hideout' is the wordplay.
'the parisian' becomes 'le' (definite article in French).
'back' shows that the letters should be reversed in order.
'in' means one lot of letters goes inside another.
'unusual' is an anagram indicator.
'le' back-to-front is 'el'.
'hideout' with letters rearranged gives 'hotdieu'.
'el' put into 'hotdieu' is 'HOTEL-DIEU'.

Can you help me to learn more?