Something like a football pitch (6)
I believe the answer is:
oblong
'pitch' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for oblong that I've seen before include "Oval" , "Figure with opposite sides parallel, longer in one direction" , "Rectangle with adjacent sides unequal" , "Cab" , "book form?" .)