I am guessing that this is the theme you are talking about. If so, I don’t see any specialized filters that would let you alter the character count of the excerpt. The widget does use get_the_excerpt()
so you should be able to alter the character count with Core filters though.
function excerpt_trim_cb_wpse_114219($excerpt) {
remove_filter('wp_trim_excerpt','excerpt_trim_cb_wpse_114219',1000);
return substr($excerpt,0,5);
}
function insert_into_sidebar_wpse_114219($s) {
if (
isset($s['callback'])
&& is_object($s['callback'][0])
&& 'Academica_Featured_Posts_Gallery' === get_class($s['callback'][0]))
{
add_filter(
'wp_trim_excerpt',
'excerpt_trim_cb_wpse_114219',
1000
);
}
}
add_action( 'dynamic_sidebar', 'insert_into_sidebar_wpse_114219' );