Bitterness from imprisoned geisha (4)
I believe the answer is:
edge
'bitterness' is the definition.
(thesaurus)
'from imprisoned geisha' is the wordplay.
'from' indicates a hidden word.
'EDGE' is hidden in the letters of 'imprisoned geisha'.
(Other definitions for edge that I've seen before include "Margin, outside limit" , "Guitarist with U2" , "Border; intense quality" , "Upper hand" , "Rim or slight advantage" .)