A for effort
A verbal acknowledgement of appreciation for attempting a task, even if it did not produce a successful result. You forgot to sand the wood before you painted it, but I'll give you an A for effort since you tried to help.
* A for effort
Fig. acknowledgement for having tried to do something, even if it was not successful. (*Typically: get ~; give someone ~.) The plan didn't work, but I'll give you an A for effort for trying.