More lucid student wants nitrogen after carbon (7)
I believe the answer is:
clearer
'more lucid' is the definition.
('clear' can be similar in meaning to 'lucid')
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for clearer that I've seen before include "less misty" , "Less cloudy or more easily understood" , "Less obscure" , "Less clouded, more well-defined" , "Less overcast" .)