Criminal has mostly pirated chart songs (3,6)
I believe the answer is:
hit parade
'chart songs' is the definition.
'criminal has mostly pirated' is the wordplay.
'criminal' is an anagram indicator.
'mostly' means to remove the last letter.
'has' with its last letter removed is 'ha'.
'ha'+'pirated'='hapirated'
'hapirated' anagrammed gives 'HIT PARADE'.
(Other definitions for hit parade that I've seen before include "list of winners" , "Those once charting" , "Pop charts" , "Top-selling numbers" , "Selling CDs" .)