Main canal with actual rocks? Here’s aid for sailors (8,7)

I believe the answer is:

nautical almanac

'aid for sailors' is the definition.
(guidebook used by sailors)

'main canal with actual rocks?' is the wordplay.
'with' means one lot of letters go next to another.
'rocks?' indicates anagramming the letters (I've seen 'rock' mean this).
'main'+'canal'+'actual'='maincanalactual'
'maincanalactual' is an anagram of 'NAUTICAL ALMANAC'.

'here's' is the link.

I've seen this clue in The Independent.

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