One spot round the end of the chin could be (4)
I believe the answer is:
acne
'one spot' is the definition.
(thesaurus)
'round the end of the chin could be' is the wordplay.
'round' means one lot of letters goes inside another.
'the end of the' says to take the final letters.
'could be' becomes 'ace' (I can't explain this - if you can you should give a lot more credence to this answer).
The final letter of 'chin' is 'n'.
'n' inserted within 'ace' is 'ACNE'.
Can you help me to learn more?
(Other definitions for acne that I've seen before include "(Inflammation causing) spots" , "sort of disease" , "Facial spots" , "Teenage spots" , "Skin affliction" .)