Extra support, etc., at which many scoff? (5)

I believe the answer is:

cleat

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'extra support' is the definition.
'cleat' can be an answer for 'support' (I've seen this before). I'm not sure about the 'extra' bit.

'etc at which many scoff?' is the wordplay.
'etc' becomes 'c' (I can't justify this - if you can you should give a lot more credence to this answer).
'at which' means one lot of letters go next to another.
'many' becomes 'l'.
'scoff?' becomes 'eat' (to scoff something is to eat it quickly).
'c'+'l'+'eat'='CLEAT'

Can you help me to learn more?

(Other definitions for cleat that I've seen before include "Projection to tie a rope around" , "Projection for a rope on a boat" , "Device on which to secure a rope" , "Support" , "Projection for a rope on board" .)

I've seen this clue in the Evening Standard.

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