Irrelevant old female never against series (2,2,11)
I believe the answer is:
of no consequence
'irrelevant' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.
'old female never against series' is the wordplay.
I cannot really see how this works, but
'old' could be 'o' (abbreviation) and 'o' is present in the answer.
'female' could be 'f' (abbreviation) and 'f' is present in the answer.
'never' could be 'no' (I've seen this in other clues) and 'no' is found in the answer.
'against' could be 'con' (as in pros and cons, for and against) and 'con' is found within the answer.
'series' could be 'sequence' (sequence is a kind of series) and 'sequence' is found within the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Another definition for of no consequence that I've seen is " without meaning".)