You earn even less foreign currency (4)
I believe the answer is:
yuan
'foreign currency' is the definition.
(I've seen this before)
'you earn even' is the wordplay.
'even' indicates alternate letters (even-numbered letters are used).
'you'+'earn'='youearn'
The alternate letters of 'youearn' are 'YUAN'.
'less' is the link.
This may not be right. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for yuan that I've seen before include "foreign currency" , "money abroad" , "Chinese capital" , "Chinese money" , "Oriental ready" .)