One flagging needs meal inn's prepared (8)
I believe the answer is:
linesman
'one flagging' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'meal inn's prepared' is the wordplay.
'prepared' indicates an anagram.
'meal'+'inns'='mealinns'
'mealinns' with letters rearranged gives 'LINESMAN'.
'needs' acts as a link.
Can you help me to learn more?
(Other definitions for linesman that I've seen before include "Male official with a flag" , "Referee's assistant" , "Official helping referee - telephone repairer" , "Court official" , "Touch judge" .)