Attentive (3,4)
'attentive' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for alert that I've seen before include "Danger warning" , "Put on guard, warn" , "Thinking and acting quickly" , "sharp-witted" , "Watchful and observant" .)
'attentive' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for all ears that I've seen before include "Listening attentively" , "Being very attentive" , "Very alert" , "Prepared to listen" , ".Listening very intently" .)