Device for exercising a stupid ringer (8)
I believe the answer is:
dumbbell
'device for exercising a' is the definition.
I can't tell whether this definition defines the answer.
'stupid ringer' is the wordplay.
'stupid' becomes 'dumb' (similar in meaning).
'ringer' becomes 'bell' (a bell rings).
'dumb'+'bell'='DUMBBELL'
Can you help me to learn more?
(Other definitions for dumbbell that I've seen before include "Exercise weight" , "Weight-training device" , "Short weighted bar for exercises - sounds stupid" , "Weightlifter's item" , "Short bar with weights for exercising (4-4)" .)