Cut line? What's going on in theatre's rotten (3,3)

I believe the answer is:

lop off

I'm a little stuck... Click here to teach me more about this clue!

'cut' is the definition.
The answer and definition can be both to do with contact as well as being verbs in their base form.
Perhaps they are linked in a way I don't understand?

'line? what's going on in theatre's rotten' is the wordplay.
'line?' becomes 'l'.
'what's going on in theatre' becomes 'op' (I am not sure about this - if you are sure you should believe this answer much more).
'rotten' becomes 'off' (I've seen this before).
'l'+'op'+'off'='LOP OFF'

Can you help me to learn more?

Want a hint initially instead of a full solution? Install my app