Where have you seen this?
Chances are you saw if often if you were in Australia, New Zealand, Japan or Europe during the 1989/early 1990 "Love
Town" tour. It seems that during this tour, The Edge was experimenting with the new (at the time) Clapton Model Stratocasters.
Perhaps, this was to see about replacing the older models that he owned or perhaps, merely an experiment.
It seems that the yellow Clapton saw a bit more use than the red, but there are a handful of photos from the Australian
leg of the tour of The Edge playing the red Clapton.
Post "Love Town" the Clapton models seemed to lose favor. The only one used after that tour was the pewter Clapton that
has a Rene Castro paint job applied. (snake and skeleton). The pewter Clapton was used during the ZOOTV and ZOOROPA tour performances
of "Desire" and "The Fly".
It, as all Clapton's of the era, has Golden Lace Sensor pickups and a 25db mid-boost.
* more information forthcoming