Agreed about area and temperature that is needed for brewing (5)
I believe the answer is:
yeast
'is needed for brewing' is the definition.
I can't tell whether this definition defines the answer.
'agreed about area and temperature' is the wordplay.
'agreed' becomes 'yes' ('agreed' can mean 'yes').
'about' indicates putting letters inside.
'area' becomes 'a' (maths abbreviation).
'and' is a charade indicator (letters next to each other).
'temperature' becomes 't' (abbreviation).
'yes' placed around 'a' is 'yeas'.
'yeas'+'t'='YEAST'
'that' acts as a link.
Can you help me to learn more?
(Other definitions for yeast that I've seen before include "Leavening agent in bread-making" , "lifting agent" , "Fermenting agent" , "that baker needs" , "Alcohol-producing fungus" .)