Applaud sneaky device though it's rubbish (8)
I believe the answer is:
claptrap
'it's rubbish' is the definition.
(I've seen this before)
'applaud sneaky device' is the wordplay.
'applaud' becomes 'clap' (synonyms).
'sneaky device' becomes 'trap' (trap is a kind of device. I am not sure about the 'sneaky' bit.).
'clap'+'trap'='CLAPTRAP'
'though' is the link.
Can you help me to learn more?
(Other definitions for claptrap that I've seen before include "Foolish or pretentious talk" , "Bunk" , "Contrived but foolish talk" , "Meaningless nonsense" , "Pretentious talk used to win applause" .)