“A terrible slob,” I add, “hard to get rid of” (7)
I believe the answer is:
Here is my best explanation:
'get rid of' is the definition.
('abolish' can be a synonym of 'get rid of')
'a terrible slob i add hard' is the wordplay.
'terrible' is an anagram indicator.
'add' means one lot of letters go next to another.
'hard' becomes 'h' (abbreviation used in pencil classifications).
'slobi' is an anagram of 'bolis'.
'to' acts as a link.
(Other definitions for abolish that I've seen before include "Get rid of", "Cancel or abrogate", "Do away with - end", "Axe", "Put an end to (custom)", "Annul - expunge", "Quash", "Formally do away with", "Cancel, annul" and "Put an end to, a rule perhaps".)