Unwilling group going to hospital (4)
I believe the answer is:
loth
'unwilling' is the definition.
('loth' can be similar in meaning to 'unwilling')
'group going to hospital' is the wordplay.
'group' becomes 'lot' (lot is a kind of group**).
'going to' is a charade indicator (letters next to each other).
'hospital' becomes 'h'.
'lot'+'h'='LOTH'
(Other definitions for loth that I've seen before include "Reluctant, unwilling" , "Reluctant or disinclined" , "Reluctant or averse" , "Unwilling to obey" , "Not keen" .)