Not enough excuse for not being good at basketball? (3,6)
I believe the answer is:
too little
'not enough excuse' is the definition.
I don't know anything about this answer so I cannot tell whether this works.
'for not being good at basketball?' is the wordplay.
'for' becomes 'to' (eg both can mean 'in the opinion of').
'not' becomes 'o' (I've seen this in other clues).
'being good at basketball?' becomes 'little' (I am not sure about this - if you are sure you should believe this answer much more).
'to'+'o'+'little'='TOO LITTLE'
Can you help me to learn more?
(Another definition for too little that I've seen is " insufficient".)