A thingy: utensil used at once (14)

I believe the answer is:

unhesitatingly

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'once' is the definition.
Both the definition and answer are adverbs. Maybe you can see a link between them that I don't see?

'a thingy utensil used' is the wordplay.
'used' indicates anagramming the letters.
'a'+'thingy'+'utensil'='athingyutensil'
'athingyutensil' is an anagram of 'UNHESITATINGLY'.

'at' is the link.

Can you help me to learn more?

(Other definitions for unhesitatingly that I've seen before include "without doubt" , "Like a shot" .)

I've seen this clue in The Telegraph.

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