The most common and most likely answer to this crossword clue is the 9 letter word CAUSATIVE
I've seen this crossword clue in Financial Times
C
A
U
S
A
T
I
V
E
Buddy explains!

The straight part
We know that "producing an effect" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case producing an effect = causative.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 CAUSATIVE mean?
CAUSATIVE noun- An expression of an agent causing or forcing a patient to perform an action (or to be in a certain condition).
- Acting as a cause
- Expressing a cause or causation