The most elegant steamship on Earth, clearly (6)
I believe the answer is:
classy
'the most elegant' is the definition.
I can't tell whether this defines the answer.
'steamship on earth clearly' is the wordplay.
'steamship' becomes 'ss' (nautical abbreviation).
'on' is an insertion indicator.
'earth clearly' becomes 'clay' (clay is a kind of earth. I am not sure about the 'clearly' bit.).
'ss' put into 'clay' is 'CLASSY'.
Can you help me to learn more?
(Other definitions for classy that I've seen before include "Sophisticated, stylish" , "Stylish (slang)" , "Informally stylish and superior" , "Sophisticated (colloq.)" , "Elegant and fashionable, posh" .)