Last of listener's alarm (4)
I believe the answer is:
fear
'alarm' is the definition.
(I've seen this in another clue)
'last of listener's' is the wordplay.
'last' indicates one should take the final letters.
'listener' becomes 'ear' (body part which hears or listens).
The last letter of 'of' is 'f'.
'f'+'ear'='FEAR'
(Other definitions for fear that I've seen before include "Be afraid of" , "Alarm, reverence" , "Terror" , "Dread, alarm" , "awe" .)