Good-for-nothing wife alters plan (7)
I believe the answer is:
wastrel
'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'
(Other definitions for wastrel that I've seen before include "Spendthrift" , "Good-for-nothing person" , "A useless, good for nothing fellow" , "Person who dissipates resources self-indulgently" , "Profligate" .)