Using such water, you could make dear tea! (7)
I believe the answer is:
aerated
'using such water you' is the definition.
I can't tell whether this defines the answer.
'make dear tea' is the wordplay.
'make' indicates an anagram.
'dear'+'tea'='deartea'
'deartea' is an anagram of 'AERATED'.
'could' is the link.
Can you help me to learn more?
(Other definitions for aerated that I've seen before include "hot under the collar" , "Ventilated" , "Mixed with air" , "(Of liquid) charged with gas" , "pumped up" .)