Bolster way about New Guinea then (10)

I believe the answer is:

strengthen

I'm a little stuck... Click here to teach me more about this clue!

'bolster' is the definition.
(I know this)

'way about new guinea then' is the wordplay.
'way' becomes 'st' (abbreviation for street).
'about new' becomes 'ren' (I've seen this in other clues).
'guinea' becomes 'g' (this might be a standard abbreviation of which I'm unaware).
'st'+'ren'+'g'+'then'='STRENGTHEN'

Can you help me to learn more?

(Other definitions for strengthen that I've seen before include "Bolster" , "Brace" , "Build up" , "Fortify" , "Reinforce, substantiate" .)

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

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