Cobblers give a hand with door (8)
I believe the answer is:
claptrap
'cobblers' is the definition.
(I've seen this before)
'give a hand with door' is the wordplay.
'give a hand' becomes 'clap' (as in giving applause).
'with' is a charade indicator (letters next to each other).
'door' becomes 'trap' (trap door is a kind of door).
'clap'+'trap'='CLAPTRAP'
(Other definitions for claptrap that I've seen before include "Tripe" , "moonshine" , "Cobblers" , "Bull" , "Contrived but foolish talk" .)