One may be thought repulsive to a duke (4)

I believe the answer is:

toad

I'm a little stuck... Click here to teach me more about this clue!

'one may be thought repulsive' is the definition.
I can't tell whether this definition defines the answer.

'to a duke' is the wordplay.
'duke' becomes 'd' (abbreviation).
'to'+'a'+'d'='TOAD'

Can you help me to learn more?

(Other definitions for toad that I've seen before include "Common amphibian" , "Loathsome creature" , "Ancestral hall on River Bank" , "Stout-bodied amphibian" , "Wind in Willows hall-owner" .)

I've seen this clue in The Times.

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