It's impossible to communic­ate why Paul has across and down solutions, but not laterally? (1,4,3,1,4,2,8)

'it's impossible to communicate' is the definition.

'why paul has across and down solutions but not laterally?' is the wordplay.
I cannot really see how this works, but
'why' could be 'y' and 'y' is located in the answer.
'and' could be 'n' (common abbreviation for 'and') and 'n' is located in the answer.
'down' could be 'd' and 'd' is found within the answer.
'not' could be 'o' (I've seen this in other clues) and 'o' is located in the answer.
This may be the basis of clue (or it may be nonsense).