Almost certain to go unnoticed in tower above (7)
I believe the answer is:
surpass
'tower above' is the definition.
(thesaurus)
'almost certain to go' is the wordplay.
'almost' means to remove the last letter (most of the word but not all of it).
'certain' becomes 'sure' (synonyms).
'to go' becomes 'pass' (passing is a kind of going).
'sure' with its last letter taken off is 'sur'.
'sur'+'pass'='SURPASS'
'unnoticed in' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for surpass that I've seen before include "Outstrip" , "Transcend" , "Go one better" , "Outdo" , "eclipse visible" .)