Originally clinker-built, say, sailing ship (6)
I believe the answer is:
cutter
'sailing ship' is the definition.
(I know that cutter is a type of sailing ship)
'originally clinker-built say' is the wordplay.
'originally clinker-built' becomes 'c' (I can't justify this - if you can you should believe this answer much more).
'say' becomes 'utter' (to utter something is to speak or say it).
'c'+'utter'='CUTTER'
Can you help me to learn more?
(Other definitions for cutter that I've seen before include "Sailing boat - knife, perhaps" , "Ship's boat" , "Slicing tool of fast sailing ship" , "See 1 down" , "Boat; tailor" .)