Overseas characters stuff up (4)
I believe the answer is:
etas
'overseas characters' is the definition.
'etas' can be an answer for 'characters' (I have seen 'Greek characters' mean 'etas' so perhaps 'characters' could also mean 'etas'). I am not certain of the 'overseas' bit.
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for etas that I've seen before include "Foreign characters" , "who once did menial tasks in Japan?" , "Greek characters" , "lowly workers" , "Characters in Greece" .)