Concrete in here always (4)
I believe the answer is:
real
'concrete' is the definition.
(similar in meaning)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for real that I've seen before include "Substantial" , "Type of ale" , "Not imaginary, genuine" , "In America, this estate comprises land and buildings" , "Happening in actuality" .)