Being at the top of landmark constructed in concrete (8)
I believe the answer is:
tangible
'concrete' is the definition.
(similar in meaning)
'being at the top of landmark constructed' is the wordplay.
'the top of' says to take the initial letters.
'constructed' is an anagram indicator.
The initial letter of 'landmark' is 'l'.
'being'+'at'+'l'='beingatl'
'beingatl' is an anagram of 'TANGIBLE'.
'in' acts as a link.
(Other definitions for tangible that I've seen before include "Touchable, real" , "Having real substance" , "Solid, can be touched" , "Able to be perceived by touch" , "Real, solid" .)