Filler of macerated new wood (5)
I believe the answer is:
oaken
'wood' is the definition.
Both the definition and answer are adjectives. Perhaps you can see a link between them that I don't see?
'filler of macerated new' is the wordplay.
I cannot quite see how this works, but
'of' could be 'o' and 'o' is located in the answer.
'new' could be 'n' (common abbreviation eg NT for New Testament) and 'n' is found in the answer.
The remaining letters 'ake' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for oaken that I've seen before include "Made of wood from a deciduous tree" , "Timber" , "of one wood" , "Made of particular wood" , "like some old cabinets" .)