  In this work we investigate the possibility of constraining a thawing
Quintessence scalar field model for dark energy. We propose using the imprint
of baryon acoustic oscillation (BAO) on the cross-correlation of
post-reionization 21-cm signal and galaxy weak lensing convergence field to
tomographically measure the angular diameter distance $D_A(z)$ and the Hubble
parameter $H(z)$. The projected errors in these quantities are then used to
constrain the Quintessence model parameters. We find that independent $600$hrs
radio interferometric observation at four observing frequencies $916 $MHz,
$650$ MHz, $520$ MHz and $430 $MHz with a SKA-1-Mid like radio telescope in
cross-correlation with a deep weak lensing survey covering half the sky may
measure the binned $D_A$ and $H$ at a few percent level of sensitivity. The
Monte Carlo analysis for a power law thawing Quintessence model gives the
$1-\sigma$ marginalized bounds on the initial slope $\lambda_i$,dark energy
density parameter $\Omega_{\phi 0}$ and the shape of the potential $\Gamma$ at
8.63%, 10.08% and 9.75% respectively. The constraints improve to 7.66%, 4.39%
and 5.86% respectively when a joint analysis with SN and other probes is
performed.
