Caught express to get fast boat (6)
I believe the answer is:
cutter
'fast boat' is the definition.
(type of boat)
'caught express' is the wordplay.
'caught' becomes 'c' (cricket abbreviation).
'express' becomes 'utter' (synonyms).
'c'+'utter'='CUTTER'
'to get' is the link.
(Other definitions for cutter that I've seen before include "E.g. knife" , "See 1 down" , "Sailing vessel" , "Person docking" , "Slicer, chopper, carver" .)