Piece of plywood, possibly thin, as support (6)
I believe the answer is:
plinth
'support' is the definition.
(plinth is a kind of support)
'piece of plywood possibly thin' is the wordplay.
'piece of plywood' becomes 'pl' (I can't justify this - if you can you should give a lot more credence to this answer).
'possibly' indicates an anagram.
'thin' is an anagram of 'inth'.
'pl'+'inth'='PLINTH'
'as' acts as a link.
Can you help me to learn more?
(Other definitions for plinth that I've seen before include "Support for statue or column" , "Statue's base" , "Square block under a column" , "Base supporting a statue" , "Block forming base of column or statue" .)