A lone wolf poet's destroyed in a single fierce move (2,3,4,5)
I believe the answer is:
at one fell swoop
'in a single fierce move' is the definition.
'a lone wolf poet's destroyed' is the wordplay.
'destroyed' indicates an anagram.
'lone'+'wolf'+'poets'='lonewolfpoets'
'lonewolfpoets' is an anagram of 'tonefellswoop'.
'a'+'tonefellswoop'='AT ONE FELL SWOOP'
(Other definitions for at one fell swoop that I've seen before include "all together" , "46 [AT THE SAME TIME]?" .)