Eggs are dear it's said (3)
I believe the answer is:
roe
'eggs' is the definition.
(fish eggs)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for roe that I've seen before include "eg Caviare" , "Swift runner" , "Mass of fish's eggs" , "A mass of fish-eggs" , "Lobster's ripe ovary" .)