The virtue of having spoken it in my presence (8)
I believe the answer is:
morality
'the virtue' is the definition.
(I've seen this before)
'having spoken it in my presence' is the wordplay.
I cannot quite see how this works, but
'spoken' could be 'oral' (similar in meaning) and 'oral' is found within the answer.
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is found in the answer.
This explanation may well be incorrect...
'of' is the link.
Can you help me to learn more?
(Other definitions for morality that I've seen before include "virtue" , "Sort of play" , "Principles of good and bad for my tailor" , "Ethical behaviour" , "Ethics" .)