Measure a piece of enclosed ground (4)
I believe the answer is:
yard
This could be a double definition.
'measure a piece' is the first definition.
'yard' can be an answer for 'measure' (I've seen this before). I am not sure about the 'a piece' bit.
'enclosed ground' is the second definition.
(enclosed outside area)
'of' acts as a link.
Can you help me to learn more?
(Other definitions for yard that I've seen before include "Sail support" , "Imperial unit of length" , "A little under a metre" , "3 feet" , "36 inches" .)