Suppress the endless nonsense and let loose (8)
I believe the answer is:
throttle
'suppress' is the definition.
(thesaurus)
'the endless nonsense and let loose' is the wordplay.
'endless' means to remove the last letter.
'nonsense' becomes 'rot' (I've seen this before).
'and' is a charade indicator (letters next to each other).
'loose' indicates an anagram (letters are loosened from their original positions).
'the' with its last letter taken away is 'th'.
'let' is an anagram of 'tle'.
'th'+'rot'+'tle'='THROTTLE'
(Other definitions for throttle that I've seen before include "Choke by pressure on the windpipe" , "Check" , "Accelerator pedal" , "Fuel-regulating valve in an engine" , "Strangle; regulator valve" .)