Issue returned by boy at the last moment (4,2,4)
I believe the answer is:
just in time
'at the last moment' is the definition.
'issue returned by boy' is the wordplay.
'issue' becomes 'emit' (I've seen this before).
'returned' says the letters should be written in reverse.
'by' means one lot of letters go next to another.
'boy' becomes 'justin' (I've seen this before**).
'emit' in reverse letter order is 'time'.
'time' put after 'justin' is 'JUST-IN-TIME'.
(Other definitions for just in time that I've seen before include "At the last possible moment" , "I met Justin (anag.)" .)