Wings of swan covering dull part of flower (6)
I believe the answer is:
stamen
'part of flower' is the definition.
('stamen' is part of 'flower')
'wings of swan covering dull' is the wordplay.
'wings of' says to hollow out the word (remove centre letters) (letters on the two wings removed).
'covering' indicates putting letters inside.
'dull' becomes 'tame' (I've seen this before).
'swan' with its centre taken out is 'sn'.
'sn' enclosing 'tame' is 'STAMEN'.
(Other definitions for stamen that I've seen before include "The pollen-bearing organ of flowering plants" , "Male reproductive organ of a flower" , "Male organ of plant" , "Flower pollen carrier" , "Bit of a bloomer" .)