Ladies at Glastonbury, say, give up rings at gate (6)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

At the Glastonbury Festival, the huge crowd would require portable toilets like PORTALOO (a trade name like BIC for pen and HOOVER for vacuum cleaner that has passed into normal usage) Take away the two O’s (give up rings) and you get the gate