Plant ID

This plant is the shrub Pistacia lentiscus, sometimes also called mastic or lentisk.  It is an evergreen shrub which is particularly drought resistant and grows well on dry, well drained scrubby land. It has the advantage of growing into well shaped shrubs and even small trees and can easily withstand hard pruning and shearing. The female plants have small red berries which later turn black and are much loved by birds which is why you normally find so many seedlings under trees, especially carob trees.

Its leathery leaves and deep roots make it particularly difficult to spray into oblivion, so I would suggest that you take a sample to your local agrobotiga and ask their advice
how to get rid of it.