Beat the full-back 1v1 and cross. Take him on with a change of pace to reach the byline, keep the cross away from the keeper, and deliver for the striker to finish.
The winger takes on the full-back one on one, beats him on the outside to reach the byline, and crosses for the striker to attack. The full-back defends the take-on live. Emphasise the change of pace to beat the man and a quality delivery under pressure. Vary the finish and rotate the winger, full-back, and striker.
A winger who has just beaten a full-back is travelling at speed, slightly off balance, with a defender recovering over his shoulder and perhaps a second closing from inside. The cross he delivers in that state has almost nothing in common with the one he delivers unopposed in a crossing drill, which is why players who look excellent in the isolated version disappear on a Saturday.
Joining the two skills is the entire point of this exercise, and the join is where the coaching sits. The first touch after the beat has to go into space that allows a clean swing, which usually means slightly further ahead than feels comfortable at that speed. Taken too close to the feet, the winger has to check, and checking lets the recovering defender get across to block.
The change of pace is what creates the room. Beating a defender by a yard and continuing at the same speed means crossing under pressure anyway; beating him and accelerating means two yards, which is the difference between a struck delivery and a blocked one.
Where to cross from is a decision, not a default. Reaching the byline gives the cutback angle, but only if the beat happened early enough. A winger who beats his man level with the penalty area should deliver early rather than force his way to a byline he will not reach, because the defence is not set yet and the early ball is available.
The honest note: this is a demanding rep, and against a genuinely competitive full-back most attempts will not produce a cross at all.
Save it to your private drills, then change the animation, adjust positions, swap equipment, or drop it into a session block. Or start from a blank pitch and build your own.