Impoverished duke raised flag (5)
I believe the answer is:
droop
'flag' is the definition.
(I know that flag can be written as droop)
'impoverished duke raised' is the wordplay.
'impoverished' becomes 'poor' (similar in meaning).
'duke' becomes 'd' (abbreviation).
'raised' is a reversal indicator (going up in a down clue).
'poor'+'d'='poord'
'poord' in reverse letter order is 'DROOP'.
(Other definitions for droop that I've seen before include "Sag, hang down" , "languish" , "Hang downwards, lose strength or spirit" , "sink" , "be despondent" .)