Animal in hospital, sore unfortunately (5)
I believe the answer is:
horse
'animal' is the definition.
(thesaurus)
'hospital sore unfortunately' is the wordplay.
'hospital' becomes 'h' (**).
'unfortunately' indicates anagramming the letters.
'sore' with letters rearranged gives 'orse'.
'h'+'orse'='HORSE'
'in' is the link.
(Other definitions for horse that I've seen before include "Suffolk punch" , "It may get people stoned" , "Animal providing" , "See 13" , "Equipment in gym" .)