Outwardly a variety of leek, often boiled (6)
I believe the answer is:
kettle
'outwardly a variety of leek often boiled' is the definition.
I can't tell whether this definition defines the answer.
'outwardly a variety of leek often boiled' is the wordplay.
'outwardly' means one lot of letters goes inside another (some letters go on the outside).
'a variety of' is an anagram indicator.
'often boiled' becomes 'tt' (I can't justify this - if you can you should give a lot more credence to this answer).
'leek' is an anagram of 'kele'.
'kele' enclosing 'tt' is 'KETTLE'.
Can you help me to learn more?
(Other definitions for kettle that I've seen before include "Vessel for heating liquids" , "The pot may call this black" , "A fence to catch fish" , "Spouted vessel" , "Container for heating 10" .)