Symbols in gospel linked with one or two older books (8)

I believe the answer is:

markings

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'symbols' is the definition.
(marking is a kind of symbol)

'gospel linked with one or two older books' is the wordplay.
'gospel' becomes 'mar' (I am not sure about this - if you are sure you should believe this answer much more).
'linked with' says to put letters next to each other.
'one or two older books' becomes 'Kings' (m Kings and a Kings are books of the Bible).
'mar'+'kings'='MARKINGS'

'in' acts as a link.

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I've seen this clue in The Independent.

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