Iceberg, for instance (7)
I believe the answer is:
lettuce
'iceberg for instance' is the definition.
(I know that iceberg lettuce is a type of lettuce)
This is all the clue.
(Other definitions for lettuce that I've seen before include "Salad leaves" , "Salad green" , "Cos or iceberg?" , "food" , "E.g. cos" .)