One spread out on back of board, as shown (9)
I believe the answer is:
displayed
'shown' is the definition.
(displaying is a kind of showing)
'one spread out on back of board' is the wordplay.
'one' becomes 'i' (Roman numeral).
'spread out' becomes 'splayed' (I've seen this before).
'on' says to put letters next to each other.
'back of' indicates one should take the final letters.
The last letter of 'board' is 'd'.
'i'+'splayed'='isplayed'
'isplayed' after 'd' is 'DISPLAYED'.
'as' is the link.
(Other definitions for displayed that I've seen before include "Shown publicly" , "Exhibited" , "Showed" , "show" , "revealed" .)