Wife has rings: that was careless! (6)
I believe the answer is:
whoops
'was careless' is the definition.
I can't tell whether this definition defines the answer.
'wife has rings' is the wordplay.
'wife' becomes 'w' (abbreviation).
'has' is a charade indicator (letters next to each other).
'rings' becomes 'hoops' ('hoop' can be a synonym of 'ring').
'w'+'hoops'='WHOOPS'
'that' acts as a link.
Can you help me to learn more?
(Other definitions for whoops that I've seen before include "Worrying cry" , "Exclamation after making a mistake" , "Loud cries of excitement" , "Exclamation after a mistake; wild cries" , "Oh dear! That was a mistake!" .)