The little man's hospital (5)
I believe the answer is:
barts
'hospital' is the definition.
(short for St Bartholomew's Hospital)
'the little man's' is the wordplay.
I cannot really see how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is located in the answer.
'man's' could be 'bars' and 'bars' is located in the leftover letters.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Another definition for barts that I've seen is " hospital".)