Sort of spa with elm trees (6)
I believe the answer is:
maples
'trees' is the definition.
(maple is a kind of tree)
'sort of spa with elm' is the wordplay.
'sort of' is an anagram indicator.
'with' is a charade indicator (letters next to each other).
'spa' put after 'elm' is 'elmspa'.
'elmspa' is an anagram of 'MAPLES'.
(Other definitions for maples that I've seen before include "Trees of Canada" , "Acer trees" , "Trees providing syrup" , "Acers" , "(Canadian) trees" .)