The easiest way is to use the contains method from java.lang.String:
(.contains "The Band Named Isis" "Isis")
=> true
You can also do it with regular expressions, e.g.
(re-find #"Isis" "The Band Named Isis")
=> “Isis”
(re-find #"Osiris" "The Band Named Isis")
=> nil
If you need your result to be true or false, you can wrap it in boolean:
(boolean (re-find #"Osiris" "The Band Named Isis"))
=> false