SELECT e.entertainerid, 
       e.firstname, 
       e.lastname, 
       b.customerid, 
       b.eventdate, 
       bd.category, 
       bd.duration, 
       s.specialitydescription, 
       es.entertainerspecialitycost
  FROM Entertainer e,
       BookingDetail bd,
       Booking b,
       EntertainerSpeciality es,
       Speciality s
 WHERE e.entertainerid = bd.entertainerid
   AND b.bookingid = bd.bookingid
   AND e.entertainerid = es.entertainerid
   AND s.specialityid = es.specialityid
   AND e.entertainerid = 1

The best solution is to review the query to reduce the number of WHERE clauses or use join:
SELECT e.entertainerid, 
       e.firstname, 
       e.lastname, 
       b.customerid, 
       b.eventdate, 
       bd.category, 
       bd.duration, 
       s.specialitydescription, 
       es.entertainerspecialitycost
  FROM ENTERTAINER e
  JOIN BOOKINGDETAIL bd ON bd.entertainerid = e.entertainerid
  JOIN BOOKING b ON b.bookingid = bd.bookingid
  JOIN ENTERTAINERSPECIALITY es ON es.entertainerid = e.entertainerid
  JOIN SPECIALITY s ON s.specialityid = es.specialityid
 WHERE e.entertainerid = 1