Step 1: Using inverse trigonometric identities.
We know that \( \tan^{-1} \sqrt{3} = \frac{\pi}{3} \) and \( \sec^{-1}(-2) = \frac{2\pi}{3} \), so:
\[
\tan^{-1} \sqrt{3} - \sec^{-1}(-2) = \frac{\pi}{3} - \frac{2\pi}{3} = -\frac{\pi}{3}
\]
Step 2: Conclusion.
Thus, the correct value is \( \frac{\pi}{3} \), which corresponds to option (3).