Crossword Genius

A little upset by the facts (4)

Ross

I believe the answer is:

data

'the facts' is the definition.
(thesaurus)

'a little upset by' is the wordplay.
'little' becomes 'tad'.
'upset' is a reversal indicator.
'by' is a charade indicator (letters next to each other).
'tad' written backwards gives 'dat'.
'a' after 'dat' is 'DATA'.

(Other definitions for data that I've seen before include "Results of research" , "Facts and figures as processed by computer" , "Numerical facts" , "tables, perhaps" , "Listed facts" .)

I've seen this clue in the Evening Standard.
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