Bishop, say, with difficulty picked up plant (9)

'plant' is the definition.
(butterbur is a kind of plant)

'bishop say with difficulty picked up' is the wordplay.
'bishop' becomes 'B' (abbreviation for bishop in chess).
'say' becomes 'utter' (to utter something is to speak or say it).
'with' is a charade indicator (letters next to each other).
'difficulty' becomes 'rub' (rub can mean a difficulty or problem).
'picked up' is a reversal indicator.
'rub' written backwards gives 'bur'.
'b'+'utter'+'bur'='BUTTERBUR'