In images of old Briton, said to cover island (9)
I believe the answer is:
pictorial
'in images of' is the definition.
The definition suggests a singular noun which matches the answer.
'old briton said to cover island' is the wordplay.
'old briton' becomes 'pict' (ancient people in Scotland during Roman times).
'said' becomes 'oral' (both can mean spoken).
'to cover' means one lot of letters goes inside another.
'island' becomes 'i' (geographical abbreviation).
'oral' going around 'i' is 'orial'.
'pict'+'orial'='PICTORIAL'
Can you help me to learn more?
(Other definitions for pictorial that I've seen before include "Clip a riot (anag) - graphic" , "Magazine" , "in photographs" , "Illustrated" .)