Early birds sound pleased, wanting last flower (8)
I believe the answer is:
larkspur
'flower' is the definition.
(larkspur is a kind of flower)
'early birds sound pleased wanting last' is the wordplay.
'early birds' becomes 'larks' (I've seen this before).
'sound pleased wanting last' becomes 'pur' (I can't justify this - if you can you should believe this answer much more).
'larks'+'pur'='LARKSPUR'
Can you help me to learn more?
(Other definitions for larkspur that I've seen before include "Mediterranean plant of the buttercup family" , "Flower (named after excrescence on a bird?)" , "Delphinium-like flower" , "Flower like a delphinium" , "Plant resembling a delphinium" .)