Extremely clumsy snare trapping tail of young bird (6)
I believe the answer is:
cygnet
'bird' is the definition.
(cygnet is a kind of bird)
'extremely clumsy snare trapping tail of young' is the wordplay.
'extremely' says to hollow out the word (remove centre letters).
'snare' becomes 'net' (I've seen this before).
'trapping' means one lot of letters goes inside another.
'tail of' indicates one should take the final letters.
'clumsy' with its middle taken out is 'cy'.
The last letter of 'young' is 'g'.
'cy'+'net'='cynet'
'cynet' going around 'g' is 'CYGNET'.
(Other definitions for cygnet that I've seen before include "Young water-bird" , "Immature swan" , "Young bird of a particular type" , "that's no ugly duckling" , "Small pen, perhaps?" .)