  We propose a novel method to test CP-violation in the heavy (pseudo)scalar
sector of an extended Higgs model, in which we make simultaneous use of the
$HVV$ ($V=W^\pm, Z$) and $Ht\bar{t}$ interactions of a heavy Higgs state $H$.
This is possible at the Compact Linear Collider (CLIC) by exploiting $H$
production from Vector-Boson Fusion (VBF) and decay to $t\bar{t}$ pairs. We
analyze the distribution of the azimuthal angle between the leptons coming from
top and antitop quarks, that would allow one to disentangle the CP nature of
such a heavy Higgs state. We also show its implications for the 2-Higgs-Doublet
Model (2HDM) with CP-violation.
