When oracle listener.log file grows, it is getting harder to tail logs. The log file must be reopened. There is no need to close listener service to reset the log file. After setting the logging state off just rename the log file, then set the logging state on again. Just three commands and it is done.
# lsnrctl set log_status off
# mv $ORACLE_HOME/network/log/listener.log listener.old
# lsnrctl set log_status on