White as an owl (5)
I believe the answer is:
snowy
'white' is the definition.
(similar in meaning)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for snowy that I've seen before include "- Mountains; - owl" , "Tintin's dog - describing winter weather" , "Covered in flakes" , "Like cold weather" , "Tintin's (white?) dog" .)