Jewellery from Britain and its ancient inhabitants (7)
I believe the answer is:
bangles
'britain and its ancient inhabitants' is the definition.
I can't judge whether this defines the answer.
'jewellery from' is the wordplay.
'jewellery' becomes 'bangle' (bangle is a kind of jewellery).
'from' becomes 's' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'bangle'+'s'='BANGLES'
Can you help me to learn more?
(Other definitions for bangles that I've seen before include "Baubles, - - , and beads" , "Ornaments" .)