Excelled partly through dishonesty (5)
I believe the answer is:
shone
'excelled' is the definition.
(shine can mean to excel or do well)
'partly through dishonesty' is the wordplay.
'partly' indicates the answer is hidden within the clue (part of the clue is used).
'SHONE' can be found hidden inside 'through dishonesty'.
(Other definitions for shone that I've seen before include "Gleamed" , "Radiated, emitted light" , "Excelled; glowed" , "Sparkled" , "did brilliantly" .)