Lettuce and eggs sliced by chief (7)
I believe the answer is:
romaine
'lettuce' is the definition.
(I know that romaine is a type of lettuce)
'eggs sliced by chief' is the wordplay.
'eggs' becomes 'roe' (fish eggs).
'sliced by' is an insertion indicator (some letters slice into others).
'chief' becomes 'main' (synonyms).
'roe' enclosing 'main' is 'ROMAINE'.
'and' is the link.
(Other definitions for romaine that I've seen before include "Type of lettuce - I arm one (anag)" , "Cos lettuce" , "Variety of lettuce" , "lettuce in America" , "lettuce in the US" .)