Substantial contents (7)

I believe the answer is:

filling

I believe this clue is a double definition.

'substantial' is the first definition.
(as in a filling meal)

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

(Other definitions for filling that I've seen before include "Tooth insert" , "Satisfying (meal); one given by dentist" , "Contents" , "Requirement of teeth or petrol tank?" , "Finding someone for (a post)" .)

I've seen this clue in The Guardian.

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