Precipitation beginning to settle at present (4)
I believe the answer is:
snow
'precipitation' is the definition.
(snow is a kind of precipitation)
'beginning to settle at present' is the wordplay.
'beginning to' says to take the initial letters.
'at present' becomes 'now' ('now' can be a synonym of 'at present').
The first letter of 'settle' is 's'.
's'+'now'='SNOW'
(Other definitions for snow that I've seen before include "Flakes that drift" , "Winter flakes" , "Ice flakes" , "Weather feature" , "Wintery precipitation" .)