The most common and most likely answer to this crossword clue is the 8 letter word EXCELLED
I've seen this crossword clue in The Daily Telegraph
E
X
C
E
L
L
E
D
More clues leading to the result EXCELLED
Buddy explains!

The straight part
We know that "Did well" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case did well = excelled.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 EXCELLED mean?
EXCELLED verb- To surpass someone or something; to be better or do better than someone or something.
- To be much better than others.
- To exceed, to go beyond