Large profanity, thus this compiler's disgusting! (9)
I believe the answer is:
loathsome
'disgusting' is the definition.
('loathsome' can be a synonym of 'disgusting')
'large profanity thus this compiler's' is the wordplay.
'large' becomes 'l'.
'profanity' becomes 'oath' (oath is a kind of profanity).
'thus' becomes 'so' ('so' can be a synonym of 'thus').
'this compiler' becomes 'me' (the person who is writing these clues).
'l'+'oath'+'so'+'me'='LOATHSOME'
(Other definitions for loathsome that I've seen before include "Detestable" , "gross" , "Hateful" , "Repulsive" , "15 [ABHORRENT]" .)