The Trim Tool
Trim Tool Menu Option
We don't need to leave the Smart Tool in order to engage the Trim Tool. It is one of the three selected options. But it is highlighted in red in the screenshot just so you know where it is.

Trim Tool Application
The Trim tool allows us to shorten or lengthen a clip on the timeline. See the trim tool in action below in the video below.
HOVERING OVER THE BEGINNING OR THE END OF THE CLIP engages the trim tool.
!ProTools - The Trim Tool.mp4