Vessel, tidy article, progressed smoothly (8)
I believe the answer is:
trimaran
'vessel' is the definition.
(trimaran is a kind of vessel)
'tidy article progressed smoothly' is the wordplay.
'tidy' becomes 'trim' ('trim' can be similar in meaning to 'tidy').
'article' becomes 'a' (indefinite article).
'progressed smoothly' becomes 'ran'.
'trim'+'a'+'ran'='TRIMARAN'
(Other definitions for trimaran that I've seen before include "Three-hulled boat" , "Three-hulled vessel" , "Sailing vessel" , "Ocean vessel with three hulls side by side" , "Three-hulled craft" .)