Placed within popular hospital room (6)
I believe the answer is:
inward
'placed within' is the definition.
The answer and definition are different parts of speech. However, past participle verbs and adjectives occasionally mean the same thing.
'popular hospital room' is the wordplay.
'popular' becomes 'in' ('in' can mean trendy).
'hospital room' becomes 'ward' (I've seen this before).
'in'+'ward'='INWARD'
Can you help me to learn more?
(Other definitions for inward that I've seen before include "Formerly private" , "In the mind or spirit, not outside" , "Existing in the mind - to the centre" , "Towards the centre" , "Situated on the inside" .)