Calm those getting upset about nothing (6)
I believe the answer is:
soothe
'calm' is the definition.
(I know that calm is a more specific form of the action soothe)
'those getting upset about nothing' is the wordplay.
'getting upset' indicates an anagram.
'about' indicates putting letters inside.
'nothing' becomes 'O' (looks like zero - 0).
'those' anagrammed gives 'sothe'.
'sothe' enclosing 'o' is 'SOOTHE'.
(Other definitions for soothe that I've seen before include "Cause to feel better" , "Assuage, calm" , "Console, pacify" , "'Console, comfort (6)'" , "Appease" .)