Showed assent or recognition (6)
I believe the answer is:
nodded
'showed assent or recognition' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for nodded that I've seen before include "Signified agreement" , "Indicated assent or recognition" , "Gave silent assent with head movement" , "Lowered and raised the head" , "Signalled agreement" .)