The most common and most likely answer to this crossword clue is the 7 letter word ASSAYED
I've seen this crossword clue in The Sunday Telegraph
A
S
S
A
Y
E
D
Buddy explains!
The straight part
We know that "Tested product of mine" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case tested product of mine = assayed.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 ASSAYED mean?
ASSAYED verb- To attempt (something).
- To try, attempt (to do something).
- To analyze or estimate the composition or value of (a metal, ore etc.).
- To test the abilities of (someone) in combat; to fight.
- To affect.
- To try tasting, as food or drink.