Neapolitan tide? (4)
I believe the answer is:
neap
'tide?' is the definition.
(neap is a kind of tide)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for neap that I've seen before include "Tide with least fall and rise of water" , "Tide when there is least difference between high and low water" , "Tide sketched by a pen" , "Small tide" , "Tide when there is the least variation between high and low water" .)