Ruined tower near mountain ash (5,4)
I believe the answer is:
rowan tree
'mountain ash' is the definition.
(rowan tree is a kind of mountain ash)
'ruined tower near' is the wordplay.
'ruined' indicates anagramming the letters.
'tower'+'near'='towernear'
'towernear' is an anagram of 'ROWAN-TREE'.
(Other definitions for rowan tree that I've seen before include "Another name for the mountain ash" , "It's also called the mountain ash" .)