Supporter, second on holiday (4,4)

I believe the answer is:

back rest

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'supporter' is the definition.

'second on holiday' is the wordplay.
'second' becomes 'back' (to second a motion is to back it).
'on holiday' becomes 'rest' (rest can mean a holiday or break. I am not sure about the 'on' bit.).
'back'+'rest'='BACK REST'

Can you help me to learn more?

I've seen this clue in The Telegraph.

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