Properly adjusted car lights give good illumination (3,5)
I believe the answer is:
arc lamps
'good illumination' is the definition.
I don't know anything about this answer so I can't tell whether this works.
'properly adjusted car lights' is the wordplay.
I cannot really see how this works, but
an anagram of 'car' is 'arc' which is located in the answer.
'lights' could be 'lamps' (lamp is a kind of light) and 'lamps' is found within the answer.
This accounts for all the letters.
This explanation may well be incorrect...
'give' is the link.
Can you help me to learn more?
(Other definitions for arc lamps that I've seen before include "lighting" , "One of these gives beam" , "lights" .)