Shelter king given national emblem (4)
I believe the answer is:
leek
'national emblem' is the definition.
(I've seen this before)
'shelter king given' is the wordplay.
'shelter' becomes 'lee' (as in lee side, the side sheltered from wind).
'king' becomes 'k' (abbreviation for king in chess).
'given' means one lot of letters go next to another.
'lee'+'k'='LEEK'
(Other definitions for leek that I've seen before include "Vegetable related to onions" , "Vegetable symbol of Wales" , "Plant; Welsh emblem" , "Vegetable - Welsh emblem" , "Vegetable related to the onion" .)