Felt sadly abandoned (4)
I believe the answer is:
left
'abandoned' is the definition.
(thesaurus)
'felt sadly' is the wordplay.
'sadly' indicates anagramming the letters.
'felt' anagrammed gives 'LEFT'.
(Other definitions for left that I've seen before include "political grouping" , "Punch, perhaps" , "quit" , "not consumed" , "One < side" .)