Cut can be done with CMD+C and then I think it's CMD+Alt+V for paste and remove original.
Keyboard support in OSX is truly appalling. Window management with the keyboard is also a pain, and even tabbing through controls - even with the stupidly-off-by-default setting - sometimes fails. The reason this annoys me so much is that OSX on Mac hardware is almost a dream setup apart from these flaws, but these flaws are significant enough that, after 4 happy years, I'm actually considering switching back to Windows.
On my Mac, cut is command-x.