  The excitation of a $\Delta$-isobar in a finite nucleus in charge--exchange
($^3\!$He,t) reaction is discussed in terms of a nuclear response function. The
medium effects modifying a $\Delta$- and a pion propagation were considered for
a finite size nucleus. The Glauber approach has been used for distortion of a
$^3\!$He and a triton in the initial and the final states. The effects
determining the peak positions and its width are discussed. Large displacement
width for the $\Delta$ - h excitations and considerable contribution of
coherent pion production were found for the reaction on $^{12}$C.
