The most common and most likely answer to this crossword clue is the 6 letter word LEERED
I've seen this crossword clue in The Times
L
E
E
R
E
D
Buddy explains!

The straight part
We know that "eyed with disdain" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case eyed with disdain = leered.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 LEERED mean?
LEERED verb- To look sideways or obliquely; now especially with sexual desire or malicious intent.
- To entice with a leer or leers.
- To teach.
- To learn.