Saying, on turning it round, it is covered in flies (7)
I believe the answer is:
stating
'saying' is the definition.
('state' can be a synonym of 'say')
'round it is covered in flies' is the wordplay.
'round' says the letters should be written in reverse.
'is covered in' is an insertion indicator.
'flies' becomes 'gnats'.
'it' put inside 'gnats' is 'gnitats'.
'gnitats' backwards is 'STATING'.
'on turning it' acts as a link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Another definition for stating that I've seen is " Swearing".)