Noah may be relaxed about source of gopher wood (8)
I believe the answer is:
mahogany
'wood' is the definition.
(mahogany is a kind of wood)
'noah may be relaxed about source of gopher' is the wordplay.
'be relaxed' indicates anagramming the letters.
'about' is an insertion indicator.
'source of' suggests taking the first letters.
The initial letter of 'gopher' is 'g'.
'noah'+'may'='noahmay'
'noahmay' anagrammed gives 'mahoany'.
'mahoany' enclosing 'g' is 'MAHOGANY'.
(Other definitions for mahogany that I've seen before include "Reddish-brown wood" , "Tropical timber" , "Hogmanay? (anag)" , "Type of wood" , "tree" .)