The most common and most likely answer to this crossword clue is the 5 letter word MINED
M
I
N
E
D
More clues leading to the result MINED
- Dug stuff up
- Dug up material coming over
- Extracted material to be brought up
- Opinion being heard, proceeded secretly
- European in intelligence worked underground
- Beware of reported laid explosives
- Excavated and raised material
- Extracted opinion in hearing
- Dug up object in auditorium
- Like coal maybe, as material brought to surface
Buddy explains!

The straight part
We know that "proceeded secretly" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case proceeded secretly = mined.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 MINED mean?
MINED verb- To remove (ore) from the ground.
- To dig into, for ore or metal.
- To sow mines (the explosive devices) in (an area).
- To damage (a vehicle or ship) with a mine (an explosive device).
- To dig a tunnel or hole; to burrow in the earth.
- To dig away, or otherwise remove, the substratum or foundation of; to lay a mine under; to sap; to undermine.
- (by extension) To ruin or destroy by slow degrees or secret means.
- To pick one's nose.
- To earn new units of cryptocurrency by doing certain calculations.