Some graced a rowan tree (5)
I believe the answer is:
cedar
'tree' is the definition.
(cedar is a kind of tree)
'some graced a rowan' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'CEDAR' is hidden within 'graced a rowan'.
(Other definitions for cedar that I've seen before include "Leaving body" , "Deodar" , "Raced around noble tree" , "representative of Lebanon?" , "Fragrant conifer" .)