Crossword Genius

A lot must, surprisingly revealing all? (3,5)

Ross

I believe the answer is:

sum total

'all?' is the definition.
(thesaurus)

'a lot must surprisingly' is the wordplay.
'surprisingly' indicates an anagram.
'a'+'lot'+'must'='alotmust'
'alotmust' is an anagram of 'SUM TOTAL'.

'revealing' is the link.

(Other definitions for sum total that I've seen before include "The lot" , "Result of addition" , "The final aggregate" , "Final addition" .)

I've seen this clue in The Telegraph.
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