  The XXL survey is the largest survey carried out by XMM-Newton. Covering an
area of 50deg$^2$, the survey contains $\sim450$ galaxy clusters out to a
redshift $\sim$2 and to an X-ray flux limit of
$\sim5\times10^{-15}erg\,s^{-1}cm^{-2}$. This paper is part of the first
release of XXL results focussed on the bright cluster sample. We investigate
the scaling relation between weak-lensing mass and X-ray temperature for the
brightest clusters in XXL. The scaling relation is used to estimate the mass of
all 100 clusters in XXL-100-GC. Based on a subsample of 38 objects that lie
within the intersection of the northern XXL field and the publicly available
CFHTLenS catalog, we derive the $M_{WL}$ of each system with careful
considerations of the systematics. The clusters lie at $0.1<z<0.6$ and span a
range of $ T\simeq1-5keV$. We combine our sample with 58 clusters from the
literature, increasing the range out to 10keV. To date, this is the largest
sample of clusters with $M_{WL}$ measurements that has been used to study the
mass-temperature relation. The fit ($M\propto T^b$) to the XXL clusters returns
a slope $b=1.78^{+0.37}_{-0.32}$ and intrinsic scatter $\sigma_{\ln
M|T}\simeq0.53$; the scatter is dominated by disturbed clusters. The fit to the
combined sample of 96 clusters is in tension with self-similarity,
$b=1.67\pm0.12$ and $\sigma_{\ln M|T}\simeq0.41$. Overall our results
demonstrate the feasibility of ground-based weak-lensing scaling relation
studies down to cool systems of $\sim1keV$ temperature and highlight that the
current data and samples are a limit to our statistical precision. As such we
are unable to determine whether the validity of hydrostatic equilibrium is a
function of halo mass. An enlarged sample of cool systems, deeper weak-lensing
data, and robust modelling of the selection function will help to explore these
issues further.
