Some nips of actors revealed by that very act (4,5)
I believe the answer is:
ipso facto
'that very act' is the definition.
I can't judge whether this definition defines the answer.
'some nips of actors revealed' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'IPSO-FACTO' is hidden within 'nips of actors revealed'.
'by' acts as a link.
Can you help me to learn more?
(Other definitions for ipso facto that I've seen before include "By that very fact" , "Thereby (Latin)" , "By that very deed" , "as a result" , "By that very act (Lat.)" .)