Conditions that might affect mail etc (7)
I believe the answer is:
climate
'conditions that might' is the definition.
'climate' can be an answer for 'conditions' (I have seen 'Atmospheric conditions' mean 'climate' so perhaps 'conditions' could also mean 'climate'). I am not certain of the remainder of the definition.
'affect mail etc' is the wordplay.
'affect' indicates an anagram (I've seen 'affecting' mean this).
'mail'+'etc'='mailetc'
'mailetc' anagrammed gives 'CLIMATE'.
Can you help me to learn more?
(Other definitions for climate that I've seen before include "The regular weather conditions of a region" , "National weather conditions" , "Cite Mal (anag.)" , "Prevailing state" , "Prevailing trend" .)