Endless line after line - how lorries are handled in ferries (4)

I believe the answer is:

roro

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'lorries are handled in ferries' is the definition.
I don't know anything about this answer so I cannot judge whether this works.

'endless line after line how' is the wordplay.
'endless' means to remove the last letter.
'line' becomes 'row' (a row or line of things).
'after' says to put letters next to each other.
'line how' becomes 'ro' (I can't explain this - if you can you should believe this answer much more).
'row' with its final letter taken away is 'ro'.
'ro'+'ro'='RORO'

Can you help me to learn more?

(Other definitions for roro that I've seen before include "ferry" , "Transport" .)

I've seen this clue in The Irish Times.

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