Finish Spurs nightmare (8)

I believe the answer is:

eggshell

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'finish' is the definition.
(I've seen this before)

'spurs nightmare' is the wordplay.
'spurs' becomes 'eggs' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'nightmare' becomes 'hell'.
'eggs'+'hell'='EGGSHELL'

Can you help me to learn more?

(Other definitions for eggshell that I've seen before include "Hard cover of an ovum" , "Kind of porcelain" , "Type of translucent porcelain" , "Type of paint finish" , "fragile defence?" .)

I've seen this clue in The Sun.

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