Pale following motorway blunder (7)
I believe the answer is:
mistake
'blunder' is the definition.
(both can mean an error)
'pale following motorway' is the wordplay.
'pale' becomes 'stake' (I've seen this in another clue).
'following' says to put letters next to each other.
'motorway' becomes 'MI' (resembles Ms, English motorway).
'stake' after 'mi' is 'MISTAKE'.
(Other definitions for mistake that I've seen before include "Oversight" , "Slip" , "16 down" , "Error" , "Wrong action or judgment" .)