See (https://www.bristol.gov.uk/forms/street-cleansing) for full details. It covers all kinds of waste found on the street from abandoned cars to sex and drug litter.
The problems affecting Clifton mostly are:
Street cleansing issues can be reported to the Council by phoning 0117 922 2100.
To report fly tipping: BCC: Flytipping
In the case of fly posting, CHIS encourages the general public to remove the posters if it is safe to do so. Both fly tipping and fly posting are offences and will be prosecuted whenever it is possible to trace the culprits.