Stylish steamship in ceramic material (6)
I believe the answer is:
classy
'stylish' is the definition.
(similar in meaning)
'steamship in ceramic material' is the wordplay.
'steamship' becomes 'ss' (nautical abbreviation).
'in' means one lot of letters goes inside another.
'ceramic material' becomes 'clay' (ceramics are made of clay).
'ss' going inside 'clay' is 'CLASSY'.
(Other definitions for classy that I've seen before include "Elegant and fashionable, posh" , "showing style ..." , "Sophisticated (colloq.)" , "Sophisticated, stylish" , "Informally stylish and superior" .)