Cross the water in the direction of Land's End (4)
I believe the answer is:
ford
'cross' is the definition.
(to ford a stream is to cross it)
'water in the direction of land's end' is the wordplay.
'water in the direction of' becomes 'for' (I can't explain this - if you can you should believe this answer much more).
'end' says to take the final letters.
The last letter of 'land' is 'd'.
'for'+'d'='FORD'
'the' acts as a link.
Can you help me to learn more?
(Other definitions for ford that I've seen before include "River or stream crossing" , "Harrison - - (film actor)" , "Car - river crossing" , "Shallow place for river crossing" , "US President - river crossing" .)