Guides plan a descent taking in waterside walks (10)
I believe the answer is:
esplanades
'waterside walks' is the definition.
'guides plan a descent taking in' is the wordplay.
'taking in' says the answer is hidden in the clue (the answer has been taken into the clue).
'ESPLANADES' is hidden within 'guides plan a descent'.
(Other definitions for esplanades that I've seen before include "seaside walks" , "Seafront walks" , "Places to stroll" , "go to seaside resorts for such" .)