Really like the Thing's finger (5)

I believe the answer is:

digit

'finger' is the definition.
(I know that finger can be written as digit)

'really like the thing's' is the wordplay.
'really like' becomes 'dig' (to dig can mean to appreciate or 'get').
'the thing' becomes 'it'.
'dig'+'it'='DIGIT'

(Other definitions for digit that I've seen before include "One's on hand" , "A small number" , "Finger; number" , "Single figure - finger" , "Single number" .)

I've seen this clue in The Sunday Times and The Times.

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