Yes, elm could be suitable (6)
I believe the answer is:
seemly
'suitable' is the definition.
(thesaurus)
'yes elm could be' is the wordplay.
'could be' indicates anagramming the letters.
'yes'+'elm'='yeselm'
'yeselm' with letters rearranged gives 'SEEMLY'.
(Other definitions for seemly that I've seen before include "Decorous, in good taste" , "Decorous or proper" , "'Decorous, dignified (6)'" , "Conforming to accepted notions of propriety" , "Decent - handsome" .)