What tells you to stop getting led astray -- with proper protection (3,5)
I believe the answer is:
red light
'what tells you to stop' is the definition.
(traffic light)
'led astray with proper protection' is the wordplay.
I cannot really see how this works, but
an anagram of 'led' is 'edl' which is within the answer.
'proper' could be 'right' ('right' can be a synonym of 'proper') and 'right' is located in the leftover letters.
This accounts for all the letters.
This explanation may well be incorrect...
'getting' is the link.
(Other definitions for red light that I've seen before include "Danger signal" , "Don't go through it!" , "Danger sign" , "such a district is vicious" , "Signal not to go on!" .)