  Close encounter between a star and a supermassive black hole (SMBH) results
in the tidal disruption of the star, known as a tidal disruption event (TDE).
Recently, a few TDEs, e.g., ASASSN-15oi and AT2018hyz, have shown late-time
(hundreds of days after their UV/optical peaks) radio flares with radio
luminosities of $10^{38\sim39}$ erg/s. The super-Eddington fallback or
accretion in a TDE may generate a mass outflow. Here we investigate a scenario
that the late-time radio flares come from the interaction of the outflow with
the circum-nuclear gaseous clouds, in addition to the slow-evolving emission
component due to the outflow-diffuse medium interaction. We calculate the
associated radio temporal and spectral signatures and find that they reproduce
well the observations. The outflows have the inferred velocity of 0.2$\sim0.8$
c, the total mass of $10^{-3}\sim10^{-1}$ $\mathrm{M_{\odot}}$ and the ejection
duration of a month to a year. The distances of the clouds to the SMBH are
$0.1\sim1$ pc. This scenario has advantages in explaining the long delay,
sharpness of the rise and the multiplicity of the late radio flares. Future
observations may build up a much larger sample of late-time radio flares and
enable their use as a probe of the TDE physics and the host circumnuclear
environment.
