Complex sentence: Having grew up in a rough neighbourhood in Bukit Merah View, where there were fights and drug addicts on the streets, Tan became a gangster in his teens whose bad drinking habits often led to fights and sleeping on the streets.
Split into simpler sentences: Having grew up in a rough neighbourhood in Bukit Merah View, where there were fights and drug addicts on the streets, Tan became a gangster in his teens. He had a bad drinking habits which often led to fights and sleeping on the streets.