Stick to imitation gems (5)
I believe the answer is:
paste
I believe this is a triple definition!
'stick to' is the first definition.
(I've seen this before)
'imitation' is the second definition.
(thesaurus)
'gems' is the third definition.
(I have seen 'Artificial gems ' mean 'paste' so perhaps 'gems' could also mean 'paste')
(Other definitions for paste that I've seen before include "Thoroughly beat" , "Wallpaper glue" , "It may be put on teeth" , "food preparation" , "Watery cement" .)