Godless person at robbery (7)
I believe the answer is:
atheist
'godless person' is the definition.
(I've seen this before)
'at robbery' is the wordplay.
'robbery' becomes 'heist' (heist is a kind of robbery).
'at'+'heist'='ATHEIST'
(Other definitions for atheist that I've seen before include "One who disbelieves the existence of gods" , "Sceptic" , "One denying existence of a god" , "Person who believes there is no God" , "God denier" .)