"Deep breath ... " (4,4)
'deep breath?' is the definition.
The definition and answer can be both types of natural phenomena as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'deep breath?' is the wordplay.
'deep' becomes 'sea' (the deep can mean the sea).
'breath?' becomes 'breeze' (breath is a kind of breeze).
'sea'+'breeze'='SEA-BREEZE'
Can you help me to learn more?
(Other definitions for sea breeze that I've seen before include "Maritime wind" , "Doctor" , "Gentle coastal wind" , "Gentle wind from the ocean" , "Vodka-based cocktail" .)