Deception from Donnelly in Galway (5)
I believe the answer is:
lying
'deception' is the definition.
(I know that lying is a type of deception)
'from donnelly in galway' is the wordplay.
'from' indicates the answer is hidden within the clue.
'LYING' is hidden within 'donnelly in galway'.
(Other definitions for lying that I've seen before include "possibly, to be mendacious" , "Telling fibs" , "Spread out" , "Mendacious; recumbent" , "not to be trusted?" .)