Give evidence from stand, then watch (4,7)
I believe the answer is:
bear witness
'give evidence' is the definition.
'stand then watch' is the wordplay.
'stand then' becomes 'bear' ('bear' can be a synonym of 'stand'. I am not sure about the 'then' bit.**).
'watch' becomes 'witness' (witnessing is a kind of watching).
'bear'+'witness'='BEAR WITNESS'
'from' acts as a link.
Can you help me to learn more?
(Other definitions for bear witness that I've seen before include "Give testimony" , "Testify (to)" .)