Appear to discover (4,2)
I believe the answer is:
turn up
I believe this clue is a double definition.
'appear' is the first definition.
(I know that turn up is a more specific form of the action appear)
'discover' is the second definition.
(thesaurus)
'to' acts as a link.
(Other definitions for turn up that I've seen before include "Show" , "Arrive (uninvited?)" , "make louder" , "Increase strength" , "put in an appearance" .)