Hearing what you can do on line, one's enthralled (4)
I believe the answer is:
serf
This could be a double definition.
'hearing' is the first definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'what you can do on line one's enthralled' is the second definition.
The definition suggests a singular noun which matches the answer.
Can you help me to learn more?
(Other definitions for serf that I've seen before include "Feudal estate worker" , "who got into bondage" , "Subservient labourer" , "Medieval villein" , "Tied estate worker" .)