The OALD has an entry for 'come across' (also 'come over') with the meaning to be understood, giving this example a reader this example.

'He spoke for a long time but his meaning didn't really come across'.

And I thought whether in a situation where I don't understand the meaning of what I am being told I can employ this phrasal verb. For example, the dialog

- Very difficult to understand speech of an opponent of mine.
- Sorry, you don't come across. Could you please make yourself any clearer?