  We present a multi-wavelength investigation of a C-class flaring activity
that occurred in the active region NOAA 12734 on 8 March 2019. The
investigation utilises data from AIA and HMI on board the SDO and the
Udaipur-CALLISTO solar radio spectrograph of the Physical Research Laboratory.
This low intensity C1.3 event is characterised by typical features of a long
duration event (LDE), viz. extended flare arcade, large-scale two-ribbon
structures and twin coronal dimmings. The eruptive event occurred in a coronal
sigmoid and displayed two distinct stages of energy release, manifested in
terms of temporal and spatial evolution. The formation of twin dimming regions
are consistent with the eruption of a large flux rope with footpoints lying in
the western and eastern edges of the coronal sigmoid. The metric radio
observations obtained from Udaipur-CALLISTO reveals a broad-band
($\approx$50-180 MHz), stationary plasma emission for $\approx$7 min during the
second stage of the flaring activity that resemble a type IV radio burst. A
type III decametre-hectometre radio bursts with starting frequency of
$\approx$2.5 MHz precedes the stationary type IV burst observed by
Udaipur-CALLISTO by $\approx$5 min. The synthesis of multi-wavelength
observations and Non-Linear Force Free Field (NLFFF) coronal modelling together
with magnetic decay index analysis suggests that the sigmoid flux rope
underwent a zipping-like uprooting from its western to eastern footpoints in
response to the overlying asymmetric magnetic field confinement. The
asymmetrical eruption of the flux rope also accounts for the observed
large-scale structures viz. apparent eastward shift of flare ribbons and post
flare loops along the polarity inversion line (PIL), and provides an evidence
for lateral progression of magnetic reconnection site as the eruption proceeds.
