Just a little letter from abroad (4)
I believe the answer is:
iota
'letter from abroad' is the definition.
(letter of the Greek alphabet)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for iota that I've seen before include "Contrivance" , "(Not one) little bit" , "Greek letter of little value" , "Just a jot, like Greek letter" , "The smallest possible amount, or the Greek i" .)