Crossword Genius

Almost certain to go top (7)

Ross

I believe the answer is:

surpass

'top' 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 removed is 'sur'.
'sur'+'pass'='SURPASS'

(Other definitions for surpass that I've seen before include "Outstrip" , "supply best" , "Transcend" , "Excel" , "eclipse visible" .)

I've seen this clue in The Times.
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