Is there still allocative efficiency when a subsidy is placed on a good? An answer schedule for a practice exam I am doing states that when a subsidy is placed on a a good by the government, there is a loss of allocative efficiency.

I have also learnt from this video that when supply and demand change, the market will still be allocatively efficient, although the amount of consumer and producer surplus will change. However, the video does not take into account dead-weight loss.

When a subsidy is placed on a good by the government, there is obviously a loss in welfare due to the dead weight loss. By my question is this: is there still a point of allocative efficiency in the market of a good with a subsidy, or is there no longer allocative efficiency at all when there is a dead weight loss?
allocative efficiency occurs whenever total market surplus is maximized. This occurs whenever price is equal to the ‘free market’ equilibrium price. There is no surplus of goods at this equilibrium price. There is no DWL at this equilibrium. If there exists DWL, the market is not operating at the 'free market' (as phrased in a comment below) or the ‘unfettered’ equilibrium and the market is not allocatively efficient. To be clear, this market will still operate at some equilibrium. However, this equilibrium will not be efficient.