Marks in Germany invested in playing tennis (7)

I believe the answer is:

indents

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'marks' is the definition.
The answer and definition can be both related to communication as well as being plural nouns.
Maybe you can see a link between them that I can't see?

'germany invested in playing tennis' is the wordplay.
'germany' becomes 'd' (vehicle registration code for Deutschland).
'invested in' is an insertion indicator.
'playing' is an anagram indicator.
'tennis' with letters rearranged gives 'inents'.
'd' going within 'inents' is 'INDENTS'.

'in' is the link.

Can you help me to learn more?

(Other definitions for indents that I've seen before include "Notches" , "orders from abroad" .)

I've seen this clue in The Guardian.

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