Used bad language, maybe worse (5)
I believe the answer is:
swore
'used bad language' is the definition.
(I've seen this in another clue)
'maybe worse' is the wordplay.
'maybe' indicates anagramming the letters.
'worse' with letters rearranged gives 'SWORE'.
(Other definitions for swore that I've seen before include "Uttered profanities or avowed" , "used bad language" , "Blasphemed" , "Took oath or cursed" .)