Make a choice: revolutionary science, visual science (6)
I believe the answer is:
optics
'visual science' is the definition.
'make a choice revolutionary science' is the wordplay.
'make a choice' becomes 'opt' (I've seen this before).
'revolutionary' shows that the letters should be reversed in order.
'science' becomes 'sci' (eg in 'poli sci' for political science).
'sci' in reverse letter order is 'ics'.
'opt'+'ics'='OPTICS'
(Other definitions for optics that I've seen before include "Field of vision?" , "Science concerned with vision" , "Drink measuring devices" , "Science of light" , "Organs of sight, eyes" .)