Said "Get me water" (3)
I believe the answer is:
sea
'me water' is the definition.
'sea' can be an answer for 'water' (the sea is water). I'm not certain of the 'me' bit.
'said get' is the wordplay.
'said' indicates a 'sounds like' (homophone) clue.
'get' becomes 'see' (both can mean to understand).
'see' is a homophone of 'SEA'.
Can you help me to learn more?
(Other definitions for sea that I've seen before include "Cod's home?" , "It's stocked with fish" , "eg Dead, Red" , "Body of saltwater" , "Expanse of salt water" .)