Badly torn at the bottom - so modern (2-5)

'modern' is the definition.
I know nothing about this answer so I can't judge whether it can be defined by this definition.

'badly torn at the bottom' is the wordplay.
I cannot quite see how this works, but
an anagram of 'torn' is 'ontr' which is located in the answer.
'bottom' could be 'end' (I've seen this in other clues) and 'end' is found within the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).

'so' is the link.

Can you help me to learn more?