Brief picture of biscuits burning (8)
I believe the answer is:
snapshot
'brief picture' is the definition.
'biscuits burning' is the wordplay.
'biscuits' becomes 'snaps' (snap is a type of biscuit).
'burning' becomes 'hot' (similar in meaning).
'snaps'+'hot'='SNAPSHOT'
'of' is the link.
(Other definitions for snapshot that I've seen before include "Quickly taken photograph" , "exposure" , "pic" , "Instant record of an event" , "print" .)