Placed in water, bananas simmered (8)
I believe the answer is:
immersed
'placed in water' is the definition.
'bananas simmered' is the wordplay.
'bananas' indicates anagramming the letters (informal term for mad).
'simmered' is an anagram of 'IMMERSED'.
(Other definitions for immersed that I've seen before include "Deeply absorbed, in water or mentally" , "Simmered while covered with water" , "Steeped (in)" , "Simmered, being completely engrossed" , "Plunged into liquid" .)