Gaudy stock stuffed in pocket (8)
I believe the answer is:
tinselly
'gaudy' is the definition.
(thesaurus)
'stock stuffed in pocket' is the wordplay.
'stock' becomes 'sell'.
'stuffed in' indicates putting letters inside.
'pocket' becomes 'tiny' (pocket can mean tiny or pocket-sized).
'sell' placed inside 'tiny' is 'TINSELLY'.
(Other definitions for tinselly that I've seen before include "like glitzy decorations" , "Showy" , "just for show?" , "Showily presented" , "Like gaudy present" .)