Extra part of journey so long (3,3)
I believe the answer is:
leg bye
'extra' is the definition.
(cricket term)
'part of journey so long' is the wordplay.
'part of journey' becomes 'leg' (leg can mean a stage of a journey).
'so long' becomes 'bye' (synonyms).
'leg'+'bye'='LEG-BYE'
(Other definitions for leg bye that I've seen before include "Type of run (cricket)" , "cricketer scoring off his pad" , "Extra 24 across" , "Extra run (cricket)" .)