Swore to reform but hasn't got any better (5)
I believe the answer is:
worse
'better' is the definition.
(thesaurus)
'swore to reform' is the wordplay.
'to reform' indicates anagramming the letters (letters in a new form).
'swore' is an anagram of 'WORSE'.
'but hasn't got any' is the link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for worse that I've seen before include "Of poorer quality" , "More awful or unwell" , "Inferior to another" , "Less satisfactory" , "Opposite of better" .)