Tense, ill at ease (6)
I believe this is a double definition.
'tense' is the first definition.
(on edge can mean tense or stressed)
'ill at ease' is the second definition.
(both can mean nervous)
(Other definitions for on edge that I've seen before include "Apprehensive" , "Nervously excited" , "Cliff-top walker may be" , "Anxious, nervy" , "Highly strung" .)