IPA: /ˈtrʌb.lər/
KK: /ˈtrʌb.lɚ/
A person or thing that causes problems or disturbances.
The loud music from the party was a troubler for the neighbors.
Troubler → It is formed from "trouble" (from Old French *trouble*, meaning disturbance or confusion) and "-er" (meaning a person who). A troubler is a person who causes disturbance or confusion.
Think of someone who causes 'disturbance' ('trouble') — the '-er' just means a person. A troubler is someone who creates trouble.