a monkey on (someone's) back

American & Australian

a serious problem that will not go away.

The divorce proceedings are a monkey on her back.

• on own head be it
• on own hook
• on own time
• on pain of
• on pain of death
• on pain of something
• on paper
• on person
• on pins and needles
• on principle
• on purpose
• on radar
• on radar screen
• on record
• on safe ground
• on schedule
• on second thought
• on second thoughts
• on shaky ground
• on short notice
• on shoulders
• on side
• on sight
• on someone's account
• on someone's agenda