Gloucester are leading their opening Amlin Cup match 5-0 at half-time at Mont de Marsan thanks to a try from youngster Ian Clark.
The Cherry and Whites were struggling to find a breakthrough in the French defence despite dominating territory and possession in the opening period.
Fly-half Tim Taylor was off target with a couple of early penalties in very wet conditions before the home side could only hold out illegally.
The referee had enough of the persistent offending and sent Scottish international Scott Murray to the bin on 28 minutes but Gloucester could not gain any purchase through the pack.
Scrum-half Dave Lewis spotted a gap and was hauled down metres short of the line after breaking from the base of a ruck.
The ball was then recycled and spun out to Clark to squirt over in the corner on his European debut after half an hour.
Taylor continued his off night by missing the conversion.