Prune option sadly unsuitable (11)
I believe the answer is:
inopportune
'unsuitable' is the definition.
(thesaurus)
'prune option sadly' is the wordplay.
'sadly' indicates anagramming the letters.
'prune'+'option'='pruneoption'
'pruneoption' anagrammed gives 'INOPPORTUNE'.
(Other definitions for inopportune that I've seen before include "mistimed" , "Ill-timed" , "Not happy" , "Inconveniently timed" , "Untimely" .)