Witness in Close Encounters (3)
I believe the answer is:
see
'witness' is the definition.
(synonyms)
'in close encounters' is the wordplay.
'in' indicates a hidden word.
'SEE' is hidden in the letters of 'close encounters'.
(Other definitions for see that I've seen before include "Discern visually" , "make out" , "ecclesiastical division" , "Go out with; notice" , "Rome, notably" .)