Copy one that can't fly behind (7)
I believe the answer is:
emulate
'copy one that can't' is the definition.
'emulate' can be an answer for 'copy' (I've seen this before). I'm not certain of the rest of the definition.
'fly behind' is the wordplay.
'fly' becomes 'emu' (I can't justify this - if you can you should give a lot more credence to this answer).
'behind' becomes 'late' (as in behind schedule).
'emu'+'late'='EMULATE'
Can you help me to learn more?
(Other definitions for emulate that I've seen before include "Ape" , "Follow in the footsteps of" , "Try to do as well as, imitate" , "Imitate, try to equal" , "Model oneself on" .)