Shade trees (4)
'shade trees' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for elms that I've seen before include "may have many leaves" , "Mel's strange trees" , "Trees sound like Cockney steering devices" , "Trees (of late, prone to disease)" , "Deciduous trees with rough serrated leaves" .)
(Other definitions for maples that I've seen before include "(Canadian) trees" , "Acer trees" , "MP sale of trees" , "Trees providing syrup" , "Trees of Canada" .)