Naughty baron at it in transport bound for docks? (4,5)
I believe the answer is:
boat train
'transport bound for docks?' is the definition.
(train heading for a port)
'naughty baron at it' is the wordplay.
'naughty' is an anagram indicator.
'baron'+'at'+'it'='baronatit'
'baronatit' anagrammed gives 'BOAT-TRAIN'.
'in' is the link.
(Other definitions for boat train that I've seen before include "Transport to/from docks" , "connecting transport" , "One may be heading for a port" , "that runs down track to harbour" .)