A mere touch, possibly less than nothing (4)

I believe the answer is:

hint

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'a mere touch' is the definition.
'hint' can be an answer for 'touch' (synonyms). I'm not certain of the 'a mere' bit.

I can't explain the rest of the clue.

Can you help me to learn more?

(Other definitions for hint that I've seen before include "'Slight indication, indirect suggestion (4)'" , "Indirect clue" , "Thin sort of slight indication" , "A dash" , "Taste" .)

I've seen this clue in the Evening Standard.

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