Not taking advantage of the joker that isn’t played in (7)
I believe the answer is:
'not taking advantage of the joker' is the definition.
I can't tell whether this defines the answer.
'that isn't played in' is the wordplay.
'that' becomes 'wag' (I can't justify this - if you can you should believe this answer much more).
'played' indicates an anagram.
'in' means one lot of letters goes inside another.
'isnt' with letters rearranged gives 'stin'.
'wag' enclosing 'stin' is 'WASTING'.
Can you help me to learn more?
(Another definition for wasting that I've seen is " Spending thoughtlessly".)