Eggs in line, we hear (3)
I believe the answer is:
roe
'eggs' is the definition.
(I've seen this in other clues)
'line we hear' is the wordplay.
'line' becomes 'row' (row is a kind of line).
'we hear' shows a homophone (sound like).
'row' is a homophone of 'ROE'.
'in' is the link.
(Other definitions for roe that I've seen before include "shy animal" , "Mass of fish's eggs" , "Swift runner" , "Hoofed animal(s)" , "Lobster's ripe ovary" .)