Paying attention (9)
'paying attention' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for listening that I've seen before include "all ears" , "Hearing attentively" , "Hearing, heeding" .)
(Other definitions for interested that I've seen before include "Concerned" , "Showing curiosity" , "Wanting to know" , "prejudiced" , "Attentive" .)