Joke the wrong way about trouble or fix (4,2)
I believe the answer is:
nail up
'fix' is the definition.
I don't know anything about this answer so I cannot judge whether this works.
'joke the wrong way about trouble' is the wordplay.
'joke' becomes 'pun' (pun is a type of joke).
'the wrong way' says the letters should be written backwards.
'about' means one lot of letters goes inside another.
'trouble' becomes 'ail' (synonyms).
'pun' written backwards gives 'nup'.
'nup' enclosing 'ail' is 'NAIL UP'.
'or' is the link.
Can you help me to learn more?
(Other definitions for nail up that I've seen before include "Crucify" , "A lupin (anag.)" , "Particularly close" .)