This could make you water lawn earliest, for a change (8,4)
I believe the answer is:
artesian well
'this could make you water' is the definition.
The definition suggests a singular noun which matches the answer.
'lawn earliest for a change' is the wordplay.
'for a change' is an anagram indicator.
'lawn'+'earliest'='lawnearliest'
'lawnearliest' anagrammed gives 'ARTESIAN WELL'.
Can you help me to learn more?
(Other definitions for artesian well that I've seen before include "Bored source of water" , "device for getting water" , "Source of water with natural pressure" , "supply of water" .)