Communicating and receiving a sign (7,6)

I believe the answer is:

getting across

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'communicating' is the definition.
Although both the answer and definition are present participle verbs, I don't see how they can define each other.

'receiving a sign' is the wordplay.
'receiving' becomes 'getting' ('get' can be a synonym of 'receive').
'a sign' becomes 'across' (I can't justify this - if you can you should believe this answer much more).
'getting'+'across'='GETTING ACROSS'

'and' acts as a link.

Can you help me to learn more?

I've seen this clue in The Daily Express.

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