Calm when night falls (4)
I believe the answer is:
even
'calm' is the definition.
(I've seen this in another clue)
'when night falls' is the wordplay.
'when' becomes 'e' (I've seen this in other clues).
'night falls' becomes 'ven' (I can't explain this - if you can you should believe this answer much more).
'e'+'ven'='EVEN'
Can you help me to learn more?
(Other definitions for even that I've seen before include "All square" , "Pantomime" , "Unvarying" , "Nearly" , "Still - divisible by two" .)