  We consider higher-dimensional effective (EFT) operators consisting of
fermion dark matter (DM) connecting to Standard Model (SM) leptons upto
dimension six. Considering all operators together and assuming the DM to
undergo thermal freeze-out, we find out relic density allowed parameter space
in terms of DM mass ($m_\chi$) and New Physics (NP) scale ($\Lambda$) with one
loop direct search constraints from XENON1T experiment. Allowed parameter space
of the model is probed at the proposed International Linear Collider (ILC) via
monophoton signal for both Dirac and Majorana cases, limited by the
centre-of-mass energy $\sqrt s=$1 TeV, where DM mass can be probed within
$m_\chi<\frac{\sqrt{s}}{2}$ for the pair production to occur and $\Lambda>\sqrt
s$ for the validity of EFT framework.
