How do I Nudge clips in the timeline

Easy to do : Alt + left/right arrow to move one frame. Alt+Shift+ left/right arrow to move 5 frames.

Hmm... unless you changed to these combos from the defaults, those are actually the key combos for sliding a clip. To nudge one frame, you want Alt+, (comma) or Alt+. (period). Add Shift to move 5 frames.

Ultimately, you can make these key combos to be (just about) anything you want. These combos and many more are user customizable under Edit > Keyboard Customization.

EDIT: I should mention that as long as your clip is "free-floating"--in other words, its head and tail are not adjacent to the head or tail of any surrounding clips, the key combo Robert mentioned will work. However, if your target clip abuts one or more clips in the sequence, you'll change the duration of the surrounding clips.

For example, say that your target clip is called "B", and it is 10 frames long. The preceding clip is "A" and is also 10 frames long, and the following clip is "C" and is 10 frames long. If you "nudge" clip B one frame earlier, clip A will now be 9 frames long, because the last outgoing frame will be overlaid by B, but clip C will remain 10 frames long, and a 1 frame gap will be created between B and C.

However, if you "slide" clip B one frame earlier, clip A will again be 9 frames and clip B will remain 10 frames, but clip C will now be 11 frames long with no gap between B and C.

Sliding a clip maintains its duration and its clip in and out points, but changes its timeline in and out points. Nudging does much the same, but it is not "sticky" in the way sliding is, in that it pulls unused frames from adjacent clips into the sequence to fill gaps. Both have their use; it simply depends on the situation to dictate what you actually want to do.