Music practice — it may contain hard, boring bit (4,5)

I believe the answer is:
rock drill
'it may contain hard boring bit' is the definition.
The definition suggests a singular noun which matches the answer.
'music practice' is the wordplay.
'music' becomes 'rock' (rock music).
'practice' becomes 'drill' (synonyms).
'rock'+'drill'='ROCK-DRILL'
Can you help me to learn more?
(Another definition for rock drill that I've seen is " bore".)
I've seen this clue in The Times.
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