Dog free of lead, might one take flight? (5)
I believe the answer is:
eagle
'might one take flight?' is the definition.
(eagles can fly)
'dog free of lead' is the wordplay.
'dog' becomes 'beagle' (beagle is a kind of dog).
'free of lead' means to remove the first letter (free of its leading letter).
'beagle' with its first letter removed is 'EAGLE'.
(Other definitions for eagle that I've seen before include "may be soaring" , "A glee-ful bird?" , "one's well below par" , "Bird of prey; former children's comic" , "Bird with hooked bill and long broad wings" .)