Without trio to follow cue you can hear, defeat (5)
I believe the answer is:
worst
'defeat' is the definition.
(worst can mean to defeat)
'without trio to follow cue you can hear' is the wordplay.
'without' becomes 'wo' (abbreviation of 'without', normally with a slash).
'trio to follow cue you can hear' becomes 'RST' (RST follow Q in the alphabet - homophone of cue).
'wo'+'rst'='WORST'
(Other definitions for worst that I've seen before include "Least well" , "Make mincemeat of" , "The least favorable" , "Of the poorest quality" , "Least satisfactory" .)