See red after mist split illusion of shimmering water (6)
I believe the answer is:
mirage
'illusion of shimmering water' is the definition.
'mirage' can be an answer for 'illusion' (I've seen this before). I am not certain of the 'of shimmering water' bit.
'see red after mist split' is the wordplay.
'see red' becomes 'rage' (I've seen this in another clue).
'after' says to put letters next to each other.
'mist split' becomes 'mi' (I can't explain this - if you can you should believe this answer much more).
'rage' after 'mi' is 'MIRAGE'.
Can you help me to learn more?
(Other definitions for mirage that I've seen before include "vision" , "Illusory sighting" , "It doesn't exist" , "fantasy" , "image, not what it seems" .)