Yes, if your customer gives you a Customs Clearance document – you still need to lodge a safety and security declaration.
SSDs are required for EU countries from 1st January 2021, and from 1st July 2021 for the UK. You will also still need to submit data to the relevant pre-lodgement model for the relevant EU country (e.g. Portbase in the Netherlands, Smart Border in France, GVMS in the UK, PBN in the Republic of Ireland).
Manually these tasks are time-consuming and prone to error. If you manage your customs in CustomsLink, you can overcome these barriers.