Good-for-nothing wife alters plan (7)
I believe the answer is:
wastrel
'good-for-nothing' is the definition.
(I've seen this in another clue)
'wife alters plan' is the wordplay.
'wife' becomes 'w' (abbreviation).
'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" .)