Tim Key turned up in middle of cast leaks (6)
I believe the answer is:
admits
'leaks' is the definition.
The definition and answer can be both to do with communicating as well as being verbs in their -s form.
Perhaps you can see an association between them that I can't see?
'tim key turned up in middle of cast' is the wordplay.
'key' becomes 'd' (musical key).
'turned up' shows that the letters should be reversed in order.
'in' indicates putting letters inside.
'middle of' says to take the centre.
The centre of 'cast' is 'as'.
'tim'+'d'='timd'
'timd' in reverse letter order is 'dmit'.
'dmit' placed within 'as' is 'ADMITS'.
Can you help me to learn more?
(Other definitions for admits that I've seen before include "Allows in or accepts guilt" , "Owns up or lets in" , "Takes in" , "Lets in and confesses" , "Owns up or grants entrance to" .)