Row with newspaper boss ended fast? (5)
I believe the answer is:
dined
'ended fast?' is the definition.
(to fast is to refrain from eating or dining)
'row with newspaper boss' is the wordplay.
'row' becomes 'din' (both can mean a loud disturbance).
'with' means one lot of letters go next to another.
'newspaper boss' becomes 'ed' (I've seen this in other clues).
'din'+'ed'='DINED'
(Other definitions for dined that I've seen before include "Had supper" , "Ate a meal" .)