Smile for one providing constructive support? (4)

I believe the answer is:

beam

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This clue might be a double definition.

'smile for one' is the first definition.
'beam' can be an answer for 'smile' (to beam is to smile). I am not certain of the 'for one' bit.

'constructive support?' is the second definition.
'beam' can be an answer for 'support?' (beam is a kind of support). I'm unsure of the 'constructive' bit.

'providing' acts as a link.

Can you help me to learn more?

(Other definitions for beam that I've seen before include "giving a broad smile" , "XWD SETTER" , "Smile radiantly" , "Ray - side" , "Smile, light shaft" .)

I've seen this clue in The Times.

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