By the way, is it needed if this? (7,5)
I believe the answer is:
traffic light
'by the way is it needed if this?' is the definition.
The definition suggests a singular noun which matches the answer.
This is the entire clue.
(Other definitions for traffic light that I've seen before include "A shining contribution to road safety" , "one wants it to be green" , "Vehicle flow controller" .)