A grain in wood perhaps (5)
I believe the answer is:
acorn
'wood perhaps' is the definition.
I can't tell whether this defines the answer.
'a grain' is the wordplay.
'grain' becomes 'corn' (corn is a kind of grain).
'a'+'corn'='ACORN'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for acorn that I've seen before include "Model in stone" , "cup's content" , "Tree seed" , "old computer?" , "from which something bigger may develop" .)