Animal, pale brown, picked up noise finally -- stand still! (8)
I believe the answer is:
stagnate
'stand still' is the definition.
(to stagnate is to stop developing or decline)
'animal pale brown picked up noise finally' is the wordplay.
'animal' becomes 'stag' (stag is a kind of animal).
'pale brown' becomes 'tan' (shade of brown).
'picked up' says the letters should be written backwards.
'finally' suggests the final letters.
The final letter of 'noise' is 'e'.
'tan' written backwards gives 'nat'.
'stag'+'nat'+'e'='STAGNATE'
(Other definitions for stagnate that I've seen before include "Do nothing" , "Stop shifting" , "(Of water) become motionless" , "Cease moving" , "Stand still and become dull" .)