Loathsome guy freely snorting line (4)
I believe the answer is:
ugly
'loathsome' is the definition.
(thesaurus)
'guy freely snorting line' is the wordplay.
'freely' indicates an anagram.
'snorting' is an insertion indicator (snort can mean to ingest through the nose).
'line' becomes 'l' (used when specifying particular lines from a poem).
'guy' is an anagram of 'ugy'.
'ugy' going around 'l' is 'UGLY'.
(Other definitions for ugly that I've seen before include "Bad to look at" , "Not pleasing to look at" , "Difficult to look at" , "Hideous" , "Unprepossessing, repulsive" .)