Hi Sue,
This one has got me beat. I have been through the list of all batman characters and the only one with 5 letters is ROBIN and I don't get it.
On the cardboard theme there was a Henri Ducard: Ducard is one of Wayne's few teachers who has had a continuing presence in the comics, having taught a young Bruce Wayne the art of the manhunt. But that's 6 letters.
Can't see a sporting connection either.(Cricket)
It's time for anniec, bullfrog, trevor, mamya, aljinon, AJT or silly boy to come to the rescue!!!!