Trees, possibly sacred ... (6)
I believe the answer is:
cedars
'trees' is the definition.
(cedar is a kind of tree)
'possibly sacred' is the wordplay.
'possibly' is an anagram indicator.
'sacred' with letters rearranged gives 'CEDARS'.
(Other definitions for cedars that I've seen before include "(Lebanese?) trees" , "Sacred (anag) -- trees" , "Trees with perfumed wood" , "Strangely sacred trees" , "Aromatic trees" .)