A recoverable benefit is one which has been paid to you 'in consequence' of your personal injury.
This is so even if there are other reasons for your needing benefit- if your accident was at least partially to blame for the cause of your needing benefit, your benefits become recoverable.
If you would not have been entitled to benefit by sole reason of your accident, but another event meant that you were, then the benefit is not recoverable. It may also be that a benefit is only recoverable for a limited time (for example, if the medical expert in your case says that the accident only caused your symptoms for 12 months). Therefore even if you still received the benefit after that time, only 12 months payments would be recoverable from your damages.
Whilst it rarely ever happens, the third party is entitled to argue that you were wrongly paid a benefit. If that is accepted, then the benefit will not be recoverable from your damages. (And they will not have to repay the benefit.) However, if this happens the DWP can then reconsider your position and whether you have received benefits that you were not entitled to, in which case they may seek to recover the overpayment from you.