Somebody well-built I locked in trunk? (3,5)

I believe the answer is:

big noise

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'somebody' is the definition.
(thesaurus)

'well-built i locked in trunk?' is the wordplay.
'well built' becomes 'big' (I can't justify this - if you can you should believe this answer much more).
'locked in' is an insertion indicator.
'trunk?' becomes 'nose' (an elephant's trunk is its nose).
'i' going within 'nose' is 'noise'.
'big'+'noise'='BIG NOISE'

Can you help me to learn more?

(Other definitions for big noise that I've seen before include "Important man (colloq.)" , "Chairman" , "strong report, perhaps" , "uproar" , "Important person (colloq.)" .)

I've seen this clue in The Sunday Times.

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