Retch horribly around old Harry (6)
I believe the answer is:
hector
'harry' is the definition.
(thesaurus)
'retch horribly around old' is the wordplay.
'horribly' indicates anagramming the letters (a horribly wrong version of the letters).
'around' is an insertion indicator.
'old' becomes 'o' (abbreviation).
'retch' anagrammed gives 'hectr'.
'hectr' going around 'o' is 'HECTOR'.
(Other definitions for hector that I've seen before include "Annoy like a Trojan hero" , "'Browbeat, ballyrag (6)'" , "Bully - son of Priam" , "Greek fighter" , "Trojan prince killed by Achilles in siege of Troy" .)