Hello and welcome to BW forums
EASY is a flexible routine so you can tailor it to the individual needs and personality of your baby. If she is hungry at 6pm when she wakes from her CN there is no harm in feeding. There is no strict rule about dropping cluster feeds so you can feed at 6pm and again at BT, 7pm.
The time between 6pm - 7pm is A time but really that whole time is taken up with feeding, bathing/washing/change and getting ready for bed, the BT feed and wind down. It's quite a lot to cram in to a short time.
The CN (cat nap) is really just a short nap intended to help LO not get overtired before bed time, giving her enough energy to get through her feeds and bath.
Hope this helps.