Region in Villareal (4)
I believe the answer is:
area
'region' is the definition.
(I know that region can be written as area)
'in villareal' is the wordplay.
'in' says the answer is hidden in the clue.
'AREA' is hidden in the letters of 'villareal'.
(Other definitions for area that I've seen before include "Extent of a two-dimensional surface" , "Field -- expanse" , "Locality" , "District; plot" , "Region; extent of a surface" .)