Small source of light behind papers did nothing (5)
I believe the answer is:
idled
'did nothing' is the definition.
(I've seen this before)
'small source of light behind papers' is the wordplay.
'small source of light' becomes 'led' (abbreviation for light emitting diode; 'small' indicates an abbreviation).
'behind' is a charade indicator (letters next to each other).
'papers' becomes 'ID' (identifying documents are one's 'papers').
'led' put after 'id' is 'IDLED'.
(Other definitions for idled that I've seen before include "sat back" , "Of engine, just ticked over" , "Loitered" , "was unoccupied" , "Did little or nothing" .)