Crossword Genius

Understand it to be a figure (5)

Ross

I believe the answer is:

digit

'a figure' is the definition.
(thesaurus)

'understand it' is the wordplay.
'understand' becomes 'dig' (digging is a kind of understanding).
'dig'+'it'='DIGIT'

'to be' acts as a link.

(Other definitions for digit that I've seen before include "One in ten, say" , "Finger; number" , "one's given?" , "a number less than ten" , "using 0 or 1 for example" .)

I've seen this clue in The Telegraph.
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