Guided by the little light in the vestibule door (3)
I believe the answer is:
led
'guided' is the definition.
('lead' can be a synonym of 'guide')
'in the vestibule door' is the wordplay.
'in' says the answer is hidden in the clue.
'LED' is hidden in the letters of 'vestibule door'.
'by the little light' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for led that I've seen before include "Light-emitting diode (abbr.)" , "Came first" , "was in the van" , "Went first to show the way" , "Emitter of light" .)