Aloof crossword setter's public image, ultimately: awful (10)

I believe the answer is:

impersonal

'aloof' is the definition.
(similar in meaning)

'crossword setter's public image ultimately awful' is the wordplay.
'crossword setter's' becomes 'I'm' (I am - referring to the crossword setter).
'public image' becomes 'persona' (I've seen this before).
'ultimately' says to take the final letters.
The final letter of 'awful' is 'l'.
'im'+'persona'+'l'='IMPERSONAL'

(Other definitions for impersonal that I've seen before include "Aloof" , "Cold" , "Objective; disinterested" , "Cool" , "Ignoring one's own feelings" .)

I've seen this clue in The Everyman puzzle in The Observer.

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