A game of draughts once, one between Washington and Jefferson (5)
I believe the answer is:
adams
'a game of draughts' 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?
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for adams that I've seen before include "Father and son were American presidents" , "John Quincy --, sixth US president" , "Richard --, Watership Down author" , "Father and son US presidents" , "Of untidy appearance" .)