A city in Ohio, content from midday to nightfall (6)
I believe the answer is:
dayton
'a city in ohio' is the definition.
(I've seen this in another clue)
'content from midday to nightfall' is the wordplay.
'content' indicates the answer is hidden within the clue (I've seen 'contents of' mean this).
'DAYTON' is hidden within 'from midday to nightfall'.
(Other definitions for dayton that I've seen before include "City of Ohio" , "US city" .)