Early riser with nothing in schedule (7)
I believe the answer is:
rooster
'early riser' is the definition.
(I've seen this in another clue)
'with nothing in schedule' is the wordplay.
'with' means one lot of letters goes inside another.
'nothing in' becomes 'o' (I can't justify this - if you can you should believe this answer much more).
'schedule' becomes 'roster' (I've seen this before).
'o' inserted into 'roster' is 'ROOSTER'.
Can you help me to learn more?
(Other definitions for rooster that I've seen before include "Chanticleer" , "Early-morning caller" , "Farmyard fowl" , "Farmyard cock" , "One crows" .)