One way for a listener to use bad language (5)
I believe the answer is:
swear
'use bad language' is the definition.
(I've seen this before)
'one way for a listener' is the wordplay.
'one way' becomes 'sw' (I can't explain this - if you can you should believe this answer much more).
'for' is a charade indicator (letters next to each other).
'a listener' becomes 'ear' (I've seen this before).
'sw'+'ear'='SWEAR'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for swear that I've seen before include "Solemnly promise" , "Eff and blind" , "Use bad language" , "Assert" , "Curse" .)