Smallest in a large way! (5)

I believe the answer is:

least

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'smallest' is the definition.
(synonyms)

'in a large way' is the wordplay.
'in' is an insertion indicator.
'a large' becomes 'leat' (I can't explain this - if you can you should give a lot more credence to this answer).
'way' becomes 's' (Compass direction - South).
'leat' placed around 's' is 'LEAST'.

Can you help me to learn more?

(Other definitions for least that I've seen before include "Most insignificant" , "Superlative form of 'little'" , "Of minimal significance" , "Bottom" , "Being lowest in importance - gone stale" .)

I've seen this clue in the Evening Standard.

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