Poor female swan on river steamship (9)
I believe the answer is:
penniless
'poor' is the definition.
(similar in meaning)
'female swan on river steamship' is the wordplay.
'female swan' becomes 'pen' (I've seen this before).
'on' says to put letters next to each other (in a down clue, letters appear on others).
'river' becomes 'nile' (Nile River is an example).
'steamship' becomes 'ss' (nautical abbreviation).
'pen'+'nile'+'ss'='PENNILESS'
(Other definitions for penniless that I've seen before include "Not rich" , "Broke" , "Jack in New York" , "Skint, without a cent" , "Without money, not a cent" .)