Craving initially restrained in this temperature (6)
I believe the answer is:
thirst
'craving' is the definition.
(thirst can mean a craving or longing for something)
'initially restrained in this temperature' is the wordplay.
'initially' says to take the initial letters.
'in' indicates putting letters inside.
'temperature' becomes 't' (abbreviation).
The first letter of 'restrained' is 'r'.
'r' placed within 'this' is 'thirs'.
'thirs'+'t'='THIRST'
(Other definitions for thirst that I've seen before include "Dryness" , "Long" , "Want of drink" , "Physiological need to drink" , "Drink to slake it" .)