I came across the following quote from Martyn Lloyd-Jones’ exposition of Ephesians, where he defines “pastor-teacher” in 4:11:
The office of a pastor is generally concerned about government and instruction and rule and direction. It is borrowed, of course, from the picture of a shepherd. The shepherd shepherds his flock, keeps the sheep in order, directs them where to go and where to feed, brings them back to the fold, looks after their safety and guards them against enemies liable to attack them. It is a great office, but unfortunately it is a term which has become debased. A pastor is a man who is given charge of souls. He is not merely a nice, pleasant man who visits people and has an afternoon cup of tea with them, or passes the time of day with them. He is the guardian, the custodian, the protector, the organizer, the director, the ruler of the flock. The teacher gives instruction in doctrine, in truth (Christian Unity: An Exposition of Ephesians 4:1-16, 193).