Shape altering in a fluid way (8)
I believe the answer is:
triangle
'shape altering in a fluid way' is the definition.
'triangle' can be an answer for 'shape' (I've seen this before). I am not certain of the 'altering in a fluid way' bit.
'shape altering' is the wordplay.
'shape' indicates anagramming the letters.
'altering' anagrammed gives 'TRIANGLE'.
Can you help me to learn more?
(Other definitions for triangle that I've seen before include "Geometrical figure - musical instrument" , "Three-sided percussion instrument" , "diamond cut in half?" , "Percussion instrument of geometric origin" , "Figure - percussion instrument" .)