Decorative strip bearing motto in small capitals on mug (6)
I believe the answer is:
scroll
'decorative strip bearing motto' is the definition.
(heraldic scroll bearing a motto)
'small capitals on mug' is the wordplay.
'small capitals' becomes 'sc' (printing abbreviation).
'on' means one lot of letters go next to another.
'mug' becomes 'roll' (roll can mean to mug or rob).
'sc'+'roll'='SCROLL'
'in' is the link.
(Other definitions for scroll that I've seen before include "Coiled parchment etc" , "Ancient text" , "Old book; curl up" , "Parchment (as from the Dead Sea?)" , "Spiral or coiled design" .)