The most common and most likely answer to this crossword clue is the 6 letter word NAMELY
I've seen this crossword clue in The Sunday Telegraph
N
A
M
E
L
Y
Buddy explains!

The straight part
We know that "I.e." is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case i.e. = namely.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does NAMELY mean?
NAMELY adverb- Specifically; that is to say.
- Especially, above all.