Acted as a guide (3)
I believe the answer is:
led
'acted as a guide' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for led that I've seen before include "Guided; small light" , "Light-emitting diode (abbr.)" , "Paved the way" , "Emitter of light" , "Went first to show the way" .)