Magazine's back issue (4)
I believe the answer is:
emit
'issue' is the definition.
(thesaurus)
'magazine's back' is the wordplay.
'magazine' becomes 'time' (US magazine).
'back' is a reversal indicator.
'time' reversed gives 'EMIT'.
(Other definitions for emit that I've seen before include "Sent" , "'Give out, light say (4)'" , "Expel" , "Discharge - utter" , "Give off, gas say" .)