Worries when early rounds have not begun (4)
I believe the answer is:
eats
'worries' is the definition.
(eating is a kind of worrying)
'early rounds have not begun' is the wordplay.
'early' becomes 'es' (I can't justify this - if you can you should give a lot more credence to this answer).
'rounds' is an insertion indicator.
'have' becomes 'eat' (have can mean to eat or consume).
'not begun' means to remove the first letter (I've seen 'not beginning' mean this).
'eat' with its initial letter taken away is 'at'.
'es' going around 'at' is 'EATS'.
'when' is the link.
Can you help me to learn more?
(Other definitions for eats that I've seen before include "Food (informal)" , "Scoff" , "(Consumes) food" , "Takes meals" , "Tuck" .)