The most common and most likely answer to this crossword clue is the 5 plus 4 letter word FOOLS GOLD
I've seen this crossword clue in The Sunday Telegraph
F
O
O
L
S
G
O
L
D
More clues leading to the result FOOLS GOLD
- Lear’s companion offered to drink last of strong mineral
- Assessor rejecting second mineral that is not what it seems
- Falsified logs of former product of mine that’s deceptive
- Demons collapse according to Spooner, leaving iron compound
- Kids leave with low density ore
- Film exposes old slog taking it easy in social group
Buddy explains!
The straight part
We know that "product of mine that’s deceptive" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case product of mine that’s deceptive = fools gold.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.