Birds on seaside spot to start with, eating what they eat (7)
I believe the answer is:
ospreys
'birds' is the definition.
(osprey is a type of bird)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for ospreys that I've seen before include "Fliers" , "Large sea hawks" , "Birds that feed on fish" , "Fishing birds" , "Preys so close to fishing eagles" .)