Clear running water outside flowed by spring (11)
I believe the answer is:
transparent
'clear' is the definition.
('transparent' can be similar in meaning to 'clear')
'running water outside flowed by spring' is the wordplay.
'running water' becomes 'trent' (I've seen this before).
'outside' means one lot of letters goes inside another.
'flowed' becomes 'ran' ('run' can be a synonym of 'flow').
'by spring' becomes 'spa' (I've seen this before. I am not sure about the 'by' bit.**).
'ran'+'spa'='ranspa'
'trent' enclosing 'ranspa' is 'TRANSPARENT'.
Can you help me to learn more?
(Other definitions for transparent that I've seen before include "Open" , "Obvious - ingenuous" , "poor at lying" , "Sheer" , "Lucid - evident - clear" .)