Wind, haze and rain at the beginning and end of April (7)
I believe the answer is:
mistral
'wind' is the definition.
(I know that mistral is a type of boreas)
'haze and rain at the beginning and end of april' is the wordplay.
'haze' becomes 'mist' (I've seen this in another clue).
'and' says to put letters next to each other.
'at the beginning' indicates taking the first letters.
'and' says to put letters next to each other.
'end of' suggests removing the centre (I've seen 'ends of' mean this).
'april' with its centre removed is 'al'.
The first letter of 'rain' is 'r'.
'mist'+'r'+'al'='MISTRAL'
(Other definitions for mistral that I've seen before include "Cold dry wind in southern France" , "Famous wind in the Rhone Valley blowing towards the Med" , "Strong north wind of southern France" , "French wind" , "That's a blow" .)