Images of tragic onslaughts (5)
I believe the answer is:
icons
'images' is the definition.
('icon' can be a synonym of 'image')
'of tragic onslaughts' is the wordplay.
'of' indicates a hidden word.
'ICONS' is hidden within 'tragic onslaughts'.
(Other definitions for icons that I've seen before include "Celebrities" , "Screen symbols on 4 across" , "Religious paintings or computer symbols" , "Images, religious perhaps" , "Images or statues, or computer screen symbols" .)