The most common and most likely answer to this crossword clue is the 6 letter word THROVE
I've seen this crossword clue in The Guardian
T
H
R
O
V
E
More clues leading to the result THROVE
Buddy explains!

The straight part
We know that "progressed well" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case progressed well = throve.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 THROVE mean?
THROVE verb- To grow or increase stature; to grow vigorously or luxuriantly, to flourish.
- To increase in wealth or success; to prosper, be profitable.