Person loathsome to Bill (4)

I believe the answer is:

toad

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'person loathsome' is the definition.
I can't tell whether this defines the answer.

'to bill' is the wordplay.
'bill' becomes 'ad' (advertisement stuck on wall).
'to'+'ad'='TOAD'

Can you help me to learn more?

(Other definitions for toad that I've seen before include "Dangerous driver" , "Small amphibian" , "Warty amphibian" , "Tailless amphibian" , "Common amphibian" .)

I've seen this clue in The Sun.

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