Start to balk with hesitation? Grab a frumious thing! (12)

I believe the answer is:

bandersnatch

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'a frumious thing' is the definition.
I can't tell whether this definition defines the answer.

'start to balk with hesitation? grab' is the wordplay.
'start to' indicates taking the first letters.
'with' becomes 'and'.
'hesitation?' becomes 'er' (sound made while hesitating - um, er).
'grab' becomes 'snatch' (synonyms).
The initial letter of 'balk' is 'b'.
'b'+'and'+'er'+'snatch'='BANDERSNATCH'

Can you help me to learn more?

(Other definitions for bandersnatch that I've seen before include "It was 'frumious' in Jabberwocky" , "Lewis Carroll''s frumious monster" .)

I've seen this clue in the Sydney Morning Herald.

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