Answer
$\cot\theta\cos\theta$
Work Step by Step
$\displaystyle \csc\theta-\sin\theta=\frac{1}{\sin\theta}-\sin\theta$
$=\displaystyle \frac{1-\sin^{2}\theta}{\sin\theta}$
$=\displaystyle \frac{\cos^{2}\theta}{\sin\theta}$
$=\displaystyle \frac{\cos\theta}{\sin\theta}\times\cos\theta$
$=\cot\theta\cos\theta$