  Exploring new excitation modes and the role of the nuclear clustering has
been of great interest. An interesting speculation was made in the recent
photoabsorption measurement of $^6$Li that implied the importance of the
nuclear clustering. To understand the excitation mechanism of $^6$Li, we
perform a fully microscopic six-body calculation on the electric-dipole ($E1$)
transitions and discuss how $^6$Li is excited by the $E1$ field as a function
of the excitation energy. We show the various cluster components in the
six-body wave functions and discuss the role of the nuclear clustering in the
$E1$ excitations of $^6$Li.
