Wood in stacks sheltering a pig (8)
I believe the answer is:
mahogany
'wood' is the definition.
(mahogany is a kind of wood)
'stacks sheltering a pig' is the wordplay.
'stacks' becomes 'many' (stacks can mean many of something).
'sheltering' means one lot of letters goes inside another.
'pig' becomes 'hog' (synonyms).
'a'+'hog'='ahog'
'many' placed around 'ahog' is 'MAHOGANY'.
'in' acts as a link.
(Other definitions for mahogany that I've seen before include "Old Cornish drink" , "Hogmanay? (anag)" , "Wooden" , "Log" , "Reddish-brown hardwood" .)