We have indeterminateness of type
0/0,
i.e. limit for the numerator is
$$\lim_{x \to 0^+}\left(- \sin{\left(x \right)} + \tan{\left(x \right)}\right) = 0$$
and limit for the denominator is
$$\lim_{x \to 0^+} \sin^{3}{\left(x \right)} = 0$$
Let's take derivatives of the numerator and denominator until we eliminate indeterninateness.
$$\lim_{x \to 0^+}\left(\frac{- \sin{\left(x \right)} + \tan{\left(x \right)}}{\sin^{3}{\left(x \right)}}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{\frac{d}{d x} \left(- \sin{\left(x \right)} + \tan{\left(x \right)}\right)}{\frac{d}{d x} \sin^{3}{\left(x \right)}}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{- \cos{\left(x \right)} + \tan^{2}{\left(x \right)} + 1}{3 \sin^{2}{\left(x \right)} \cos{\left(x \right)}}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{- \cos{\left(x \right)} + \tan^{2}{\left(x \right)} + 1}{3 \sin^{2}{\left(x \right)}}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{\frac{d}{d x} \left(- \cos{\left(x \right)} + \tan^{2}{\left(x \right)} + 1\right)}{\frac{d}{d x} 3 \sin^{2}{\left(x \right)}}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{\left(2 \tan^{2}{\left(x \right)} + 2\right) \tan{\left(x \right)} + \sin{\left(x \right)}}{6 \sin{\left(x \right)} \cos{\left(x \right)}}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{\sin{\left(x \right)} + 2 \tan^{3}{\left(x \right)} + 2 \tan{\left(x \right)}}{6 \sin{\left(x \right)}}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{\frac{d}{d x} \left(\sin{\left(x \right)} + 2 \tan^{3}{\left(x \right)} + 2 \tan{\left(x \right)}\right)}{\frac{d}{d x} 6 \sin{\left(x \right)}}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{2 \left(3 \tan^{2}{\left(x \right)} + 3\right) \tan^{2}{\left(x \right)} + \cos{\left(x \right)} + 2 \tan^{2}{\left(x \right)} + 2}{6 \cos{\left(x \right)}}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{\cos{\left(x \right)}}{6} + \tan^{4}{\left(x \right)} + \frac{4 \tan^{2}{\left(x \right)}}{3} + \frac{1}{3}\right)$$
=
$$\lim_{x \to 0^+}\left(\frac{\cos{\left(x \right)}}{6} + \tan^{4}{\left(x \right)} + \frac{4 \tan^{2}{\left(x \right)}}{3} + \frac{1}{3}\right)$$
=
$$\frac{1}{2}$$
It can be seen that we have applied Lopital's rule (we have taken derivatives with respect to the numerator and denominator) 3 time(s)