Breezer has given you good advice!
Unscrew tap from wall plate (turn water off first) wrap plenty of ptfe tape on new one and screw in. If still a problem suspect water pressure.
One way of checking if it is a pressure problem is turn off water, unscrew tap off wall plate and then turn water back on for a few seconds. Ask the missus to tell you if plenty of water gushed out. If so you have good pressure (and a wet missus)