  We present observations of an M5.7 white-light flare (WLF) associated with a
small filament eruption in NOAA active region 11476 on 2012 May 10. During this
flare, a circular flare ribbon appeared in the east and a remote brightening
occurred in the northwest of the active region. Multi-wavelength data are
employed to analyze the WLF, including white light (WL), ultraviolet, extreme
ultraviolet, hard X-ray (HXR) and microwave. A close spatial and temporal
relationship between the WL, HXR and microwave emissions is found in this WLF.
However, the peak time of the WL emission lagged that of the HXR and microwave
emissions by about 1-2 minutes. Such a result tends to support the back-warming
mechanism for the WL emission. Interestingly, the enhanced WL emission occurred
at the two footpoints of the filament. Through forced and potential field
extrapolations, we find that the three-dimensional magnetic field in the flare
region has a fan-spine feature and that a flux rope lies under the dome-like
field structure. We describe the entire process of flare evolution into several
steps, each producing the sequent brightening below the filament, the circular
flare ribbons and the WL enhancement respectively. We suggest that reconnection
between the magnetic field of the filament and the overlying magnetic field or
reconnection within the flux rope leads to the WL enhancement.
