To simplify the expression \( 4 + (-6) \cdot 2 - (-3)^2 \), let's break it down step by step:
1. **Calculate \( (-6) \cdot 2 \)**:
\[
(-6) \cdot 2 = -12
\]
2. **Calculate \( (-3)^2 \)**:
\[
(-3)^2 = 9
\]
3. **Substitute these values back into the expression**:
\[
4 + (-12) - 9
\]
4. **Combine the terms**:
\( 4 + (-12) = 4 - 12 = -8 \).
Now adding \(-9\) to \(-8\):
\[
-8 - 9 = -17
\]
So, the entire expression simplifies to:
\[
-17
\]
Since the final simplified expression is a single value and not a fraction, there is no denominator involved. If you are looking for a traditional denominator in a fraction format, it would be 1 (since every integer can be expressed over 1).
Thus, the answer is:
\[
\text{The simplified denominator is } 1.
\]