Concoction full of Argentinian fruit (6)
I believe the answer is:
lichee
'fruit' is the definition.
(lichee is a kind of fruit)
'concoction full of argentinian' is the wordplay.
'concoction' becomes 'lie' (I've seen this in another clue).
'full of' means one lot of letters goes inside another.
'argentinian' becomes 'che' (I can't explain this - if you can you should believe this answer much more).
'lie' going around 'che' is 'LICHEE'.
Can you help me to learn more?
(Another definition for lichee that I've seen is " Chinese fruit".)