The lines of letters, read aloud (6)
I believe the answer is:
queues
'the lines' is the definition.
(queue is a kind of line)
'letters read aloud' is the wordplay.
I cannot quite understand how this works, but
'letters' could be 'es' (more than one E) and 'es' is located in the answer.
This explanation may well be incorrect...
'of' is the link.
Can you help me to learn more?
(Other definitions for queues that I've seen before include "Lines of waiters" , "lots of waiters" , "Lines of waiting people or vehicles" , "Waits in line" , "Line of waiting people or vehicles" .)