Panes smashed by a tree (5)
I believe the answer is:
aspen
'a tree' is the definition.
(aspen is a kind of tree)
'panes smashed' is the wordplay.
'smashed' indicates anagramming the letters.
'panes' with letters rearranged gives 'ASPEN'.
'by' is the link.
(Other definitions for aspen that I've seen before include "Tree with shivering leaves" , "Very timid" , "Trembler" , "Tmorous" , "Tremulous poplar" .)