Ships ordered by Socrates (8)
I believe the answer is:
'ships' is the definition.
The answer and definition can be both man-made objects as well as being plural nouns.
Perhaps they are linked in a way I don't understand?
'ordered by socrates' is the wordplay.
'socrates' anagrams to 'COASTERS'.
Though, I am unsure how this is indicated.
Can you help me to learn more?
(Other definitions for coasters that I've seen before include "Small table-mats" , "Small mats for Socrates" , "Merchant ships with a limited range of operation" .)