Three pounds secures ring, I report — that's sweet (8)
I believe the answer is:
lollipop
'sweet' is the definition.
(lollipop is a kind of sweet)
'three pounds secures ring i report' is the wordplay.
'three' becomes 'll' (I can't justify this - if you can you should believe this answer much more).
'pounds' becomes 'l' (L can represent the monetary pound).
'secures' indicates putting letters inside.
'ring' becomes 'o'.
'report' becomes 'pop' ('report' can mean a sudden explosive noise).
'll'+'l'='lll'
'lll' going around 'o' is 'loll'.
'loll'+'i'+'pop'='LOLLIPOP'
'that's' is the link.
(Other definitions for lollipop that I've seen before include "Sweetmeat" , "sucker" , "Sweet on a stick" , "Sweet; popular work" , "Ice confection" .)