  Finding distinct signatures of a quantum spin liquid (QSL) is an ongoing
quest in condensed matter physics, invariably complicated by the presence of
disorder in real materials. In this regard the 2D Kagome system
YCu$_3$(OH)$_6$[(Cl$_x$Br$_{(1-x)}$)$_{3-y}$(OH)$_y$] (YCOB-Cl), where the vast
mismatch in size of Y and Cu avoids subsitutional disorder, otherwise present
in kagome materials, has emerged as a favorable candidate. In crystals of this
system, with $x<$ 0.4 and no long range order, we report an unusual field
dependent magnetization $M(B)$, where $M/B$ changes linearly with $|B|$, the
absolute value of the field, in contrast to the expected quadratic behavior.
Model calculations with a distribution of ferromagnetic (FM) clusters
faithfully capture observed features suggesting such clusters to be intrinsic
to real QSL materials. YCOB-Cl has a field enhanced $T^2$ heat capacity as
expected for a Dirac QSL but lacks a linear $T$ behavior in the spin
susceptibility. By demonstrating that FM clusters dominate the contribution to
the susceptibility but not the heat capacity, our work paves the way towards
reconciling the apparent inconsistency with a Dirac QSL.
