More carried by Wessex Trains (5)
I believe the answer is:
extra
'more' is the definition.
(thesaurus)
'carried by wessex trains' is the wordplay.
'carried by' indicates the answer is hidden within the clue.
'EXTRA' is hidden within 'wessex trains'.
(Other definitions for extra that I've seen before include "More than usual" , "Cricket run; unusually" , "not included" , "An increased amount" , "One playing a minor part" .)