Softens about in short periods (7)
I believe the answer is:
minutes
'short periods' is the definition.
'minutes' can be an answer for 'periods' (minute is a kind of period). I am unsure of the 'short' bit.
'softens about in' is the wordplay.
'softens' becomes 'mutes' (muting is a kind of softening).
'about' is an insertion indicator.
'mutes' enclosing 'in' is 'MINUTES'.
Can you help me to learn more?
(Other definitions for minutes that I've seen before include "Record of a meeting's decisions" , "Record of a meeting" , "Records" , "Units of time" , "Recorded notes of a meeting" .)