  We study experimentally the lifetime of a special class of entangled states
in an atomic clock, squeezed spin states. In the presence of anisotropic noise,
their lifetime is strongly dependent on squeezing orientation. We measure the
Allan deviation spectrum of a clock operated with a phase-squeezed input state.
For integration times up to 50 s the squeezed clock achieves a given precision
2.8(3) times faster than a clock operating at the standard quantum limit.
