Wet weather at this time of year confuses one Assyrian (5,6)
I believe the answer is:
rainy season
'wet weather at this time of year' is the definition.
'rainy season' can be an answer for 'time of year' (rainy season is a kind of time of year). I am unsure of the remainder of the definition.
'confuses one assyrian' is the wordplay.
'confuses' indicates anagramming the letters.
'one'+'assyrian'='oneassyrian'
'oneassyrian' is an anagram of 'RAINY SEASON'.
Can you help me to learn more?
(Another definition for rainy season that I've seen is " Monsoon".)