Is seen to join motorway, making error, on the way (4,4)
I believe the answer is:
slip road
'the way' is the definition.
(slip road is a kind of way)
'is seen to join motorway making error' is the wordplay.
I cannot quite see how this works, but
'motorway' could be 'road' (I've seen this in another clue) and 'road' is found in the answer.
'error' could be 'slip' (slip is a kind of error) and 'slip' is found in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
'on' is the link.
Can you help me to learn more?
(Other definitions for slip road that I've seen before include "way to access motorway" , "Joining lane" , "Way to leave or join a motorway" , "Motorway access point" , "Motorway exit or entrance" .)