Every sentence should do this at a red light (4,2,1,4,4)
I believe the answer is:
come to a full stop
'every sentence should' is the definition.
I don't know anything about this answer so I can't judge whether this works.
'do this at a red light' is the wordplay.
I cannot quite understand how this works, but
'do' could be 'come' (synonyms) and 'come' is present in the answer.
'a' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for come to a full stop that I've seen before include "end" , "A period required after" .)