50 old songs played at gig coming up, including It's Not Unusual? (7)
I believe the answer is:
litotes
'50 old songs played at gig coming up' is the definition.
I can't judge whether this definition defines the answer.
'including it's not unusual?' is the wordplay.
'including' is an insertion indicator.
'not unusual?' becomes 'lotes' (I can't explain this - if you can you should give a lot more credence to this answer).
'it' placed into 'lotes' is 'LITOTES'.
Can you help me to learn more?
(Other definitions for litotes that I've seen before include "Possibly, no small surprise" , "Town of N. Norway" , "not exactly truthful, for example" , "in which not a little is a lot?" , "No exaggeration" .)