Bird comes down to earth; a marksman's target (4,6)
I believe the answer is:
clay pigeon
'target' is the definition.
(clay pigeon is a kind of target)
'bird comes down to earth a marksman's' is the wordplay.
I cannot really understand how this works, but
'bird' could be 'pigeon' (type of bird) and 'pigeon' is found in the answer.
'earth' could be 'clay' (clay is a kind of earth) and 'clay' is found in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for clay pigeon that I've seen before include "Disc fired into the air as target for shooting" , "Disc to be shot" , "Moving target" , "hard bird to shoot?" , "Trap shooter's target" .)