One of the Jonas Brothers (4)
I believe the answer is:
nick
'one of the jonas brothers' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for nick that I've seen before include "Cut; steal (colloq.)" , "Small cut; steal" , "Clink" , "The old one is devilish" , "Catch" .)