Whip's good source in reshuffle (7)
I believe the answer is:
scourge
'whip's' is the definition.
(scourge is a kind of whip)
'good source in reshuffle' is the wordplay.
'good' becomes 'g' (abbreviation).
'in reshuffle' indicates anagramming the letters (I've seen this in other clues).
'g'+'source'='gsource'
'gsource' with letters rearranged gives 'SCOURGE'.
(Other definitions for scourge that I've seen before include "Whip; agent of suffering" , "Whip - bane" , "Afflict" , "Punish severely" , "Lash; plague" .)