A capital band managed to be mediocre (7)
I believe the answer is:
alsoran
'a capital band' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.
'managed to be mediocre' is the wordplay.
'managed' becomes 'ran' (I've seen this in another clue).
'to' is a charade indicator (letters next to each other) (I've seen this in other clues).
'be mediocre' becomes 'also' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'ran' after 'also' is 'ALSORAN'.
Can you help me to learn more?
(Another definition for alsoran that I've seen is " failure?".)