Root finally cracked Belgian concrete (8)
I believe the answer is:
tangible
'concrete' is the definition.
(associated in meaning)
'root finally cracked belgian' is the wordplay.
'finally' suggests the final letters.
'cracked' is an anagram indicator.
The last letter of 'root' is 't'.
'belgian' anagrammed gives 'angible'.
't'+'angible'='TANGIBLE'
(Other definitions for tangible that I've seen before include "Real, definite" , "Touchable, real" , "Real and substantial" , "Able to be touched" , "Actual" .)