Harry has awful head gash and is in hospital (6)
I believe the answer is:
badger
'harry' is the definition.
(thesaurus)
'awful head gash and is in hospital' is the wordplay.
'awful' becomes 'bad' ('bad' can be similar in meaning to 'awful').
'head' indicates taking the first letters.
'and' means one lot of letters go next to another.
'is in hospital' becomes 'er' (I've seen this in other clues).
The initial letter of 'gash' is 'g'.
'bad'+'g'+'er'='BADGER'
'has' acts as a link.
(Other definitions for badger that I've seen before include "Black and white striped animal" , "Plague - nocturnal animal" , "Member of the weasel family" , "Pester the burrowing animal" , "Pester - nocturnal animal" .)