Part of pail leaking badly (3)
I believe the answer is:
ill
'badly' is the definition.
(eg in ill-advised)
'part of pail leaking' is the wordplay.
'part of' indicates the answer is hidden within the clue.
'ILL' is hidden in the letters of 'pail leaking'.
(Other definitions for ill that I've seen before include "Harmful" , "Shakespeare: '. . . met by moonlight'" , "Badly - in need of medical care" , "In short, the state of Chicago" , "poor" .)