Small brown bird (5-4)
'small brown bird' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for wren that I've seen before include "Very small brown songbird (4)" , "17th Century architect" , "Small bird - great architect" , "Member of the former Women's Royal Naval Service" , "Man of note" .)
(Other definitions for black swan that I've seen before include "Australian native bird" , "Aquatic bird" , "Australian winger" , "Aussie swimmer" .)