Churned up for a time, turn blue, though choppy (9)
I believe the answer is:
turbulent
'churned up for a time' is the definition.
I can't judge whether this defines the answer.
'turn blue though choppy' is the wordplay.
I cannot really understand how this works, but
'turn' could be 'u' (a 'U-turn' is a kind of turn) and 'u' is present in the answer.
an anagram of 'blue' is 'bule' which is located in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for turbulent that I've seen before include "Tempestuous" , "Violently disturbed" , "Rowdy" , "rough" , "Tumultuous" .)