The most common and most likely answer to this crossword clue is the 8 letter word HOMEBREW
H
O
M
E
B
R
E
W
Buddy explains!
The straight part
We know that "amateur product" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case amateur product = homebrew.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 HOMEBREW mean?
HOMEBREW noun- A beer brewed by enthusiasts rather than commercially.
- Anything created by enthusiasts rather than commercial entities (especially video games or amateur radio equipment).
- A player who plays for the team named after their own native town.
- To brew one's beer or other alcoholic beverage at home.
- To create something as an enthusiast, rather than using a commercial option.