Parse error unexpected 'clone' (T_CLONE), expecting '('
Welcome to SE!  Do you really mean CiviCRM 4.5? - that's really old.  The docs Jitendra points to are for the current version of Civi.  If you are back on Civi 4.5 it won't work with any version of php7.
Go back to php5.6 and plan to upgrade.  You'll want to do that in stages - see some of the other answers on here for upgrading from very old versions.