Long piece of platitudinous tripe (5)
I believe the answer is:
strip
'long piece' is the definition.
(long strip of material)
'of platitudinous tripe' is the wordplay.
'of' indicates a hidden word.
'STRIP' is hidden in the letters of 'platitudinous tripe'.
(Other definitions for strip that I've seen before include "every football club needs" , "Series of cartoon pictures - undress salaciously" , "Set of football clothes" , "sports outfit" , "Landing field - take off" .)