Confirm, and tolerate, comedian joining head (4,7)
I believe the answer is:
bear witness
'confirm' is the definition.
The definition and answer can be both to do with communicating as well as being verbs in their base form.
Perhaps you can see an association between them that I can't see?
'tolerate comedian joining head' is the wordplay.
I cannot quite understand how this works, but
'tolerate' could be 'bear' (synonyms) and 'bear' is located in the answer.
'comedian' could be 'wit' (a witty person) and 'wit' is found within the answer.
'head' could be 'ness' (ness is a headland) and 'ness' is present in the answer.
No letters remain.
This explanation may well be incorrect...
'and' is the link.
Can you help me to learn more?
(Other definitions for bear witness that I've seen before include "Give testimony" , "Testify (to)" .)