Good-for-nothing wife alters plan (7)
I believe the answer is:
wastrel
Here is my best explanation:
'good-for-nothing' is the definition.
(thesaurus)
'wife alters plan' is the wordplay.
'wife' becomes 'w'.
'plan' indicates an anagram (plan can mean organise).
'alters' anagrammed gives 'astrel'.
'w'+'astrel'='WASTREL'
This clue was last seen in Mirror