  We report $^{139}$La and $^{63}$Cu nuclear magnetic and quadrupole resonance
(NMR/NQR) studies in an underdoped La$_{1.93}$Sr$_{0.07}$CuO$_4$ single
crystal, focusing on the $^{139}$La NMR in the normal state. We demonstrate
that the local structural distortions in the low-temperature orthorhombic
structure cause the tilting of the direction of the electric field gradient
(EFG) at the nuclei from the c axis, resulting in two NMR central transition
spectra at both the $^{139}$La and $^{63}$Cu nuclei in an external field.
Taking into account the tilt angle of the EFG, the temperature dependence of
the $^{139}$La spectra allowed us to determine the $^{139}$La Knight shift and
the structural order parameter. The angle and temperature dependence of the
$^{139}$La spectrum is in perfect agreement with the macroscopic average
structure and proves a displacive transition. The $^{139}$La nuclear
spin-lattice relaxation rates, $T_1^{-1}$, suggest that
La$_{1.93}$Sr$_{0.07}$CuO$_4$ undergoes a gradual change to a
temperature-independent paramagnetic regime in the high temperature region.
Both the spectra and $T_1^{-1}$ of the $^{139}$La as a function of temperature
reveal a sharp anomaly around $T_S=387(1)$ K, implying a first-order-like
structural transition, and a dramatic change below ~70 K arising from
collective glassy spin freezing.
