Toy weapon has unusual rings to crack safe (10)
I believe the answer is:
peashooter
'toy weapon' is the definition.
(toy for shooting dried peas)
'has unusual rings to crack safe' is the wordplay.
'unusual' is an anagram indicator.
'rings' becomes 'oo' (multiple circles).
'to crack' is an insertion indicator (inserted letters crack into others).
'safe' becomes 'peter' (I've seen this in other clues).
'has' anagrammed gives 'ash'.
'ash'+'oo'='ashoo'
'ashoo' placed within 'peter' is 'PEASHOOTER'.
(Other definitions for peashooter that I've seen before include "Toy weapon" , "child's toy" , "Child's "gun"" , "Primitive weapon" .)