Said it’s the entire space (4)
I believe the answer is:
hole
'space' is the definition.
(I know that hole is a type of space)
'said it's the entire' is the wordplay.
'said' indicates a 'sounds like' (homophone) clue.
'it's the entire' becomes 'whole' (I've seen this in another clue).
'whole' is a homophone of 'HOLE'.
(Other definitions for hole that I've seen before include "Hollow, cavity" , "See 9" , "Aperture; cavity" , "Empty space; aperture" , "pocket" .)