The risk here is solely that 11 hours is not enough time. Only you can judge that. Realistically, it would take a major regional weather event at DFW which closes it to most traffic for you to no show (this isn't a connection) for your SQ flight.

AA is very efficient, particularly at DFW, about retagging bags and there are multiple backups here even if your bags don't make it on your rebooked flight.

For the benefit of others, it is worth noting that AA is pretty much alone among carriers for handling reroutes across tickets. It will do so across its own tickets or to/from OW. Thus, had OP booked DFW-SIN across multiple tickets to JL or CX, he would be fully protected. Not suggesting that those were good options here, simply that they provide protection where a transfer to a non-OW carrier does not.