Detailed bill and letter from overseas (3)
I believe the answer is:
'letter from overseas' is the definition.
I can't tell whether this defines the answer.
'detailed bill' is the wordplay.
'detailed' means to remove the last letter (the word must be end-less or 'de-tailed').
'bill' becomes 'chit' (chit is a kind of bill).
'chit' with its final letter taken away is 'CHI'.
'and' acts as a link.
Can you help me to learn more?
(Other definitions for chi that I've seen before include "Letter written by European", "T'ai -, martial art", "Mental projection", "Chinese life-force", "character from Euripides?".)