Malfunctioning lamps, a feature of church service? (5)
I believe the answer is:
psalm
'a feature of church service?' is the definition.
(psalms are often sung in a church service)
'malfunctioning lamps' is the wordplay.
'malfunctioning' indicates anagramming the letters.
'lamps' with letters rearranged gives 'PSALM'.
(Other definitions for psalm that I've seen before include "Jewish hymn" , "Lamps for a sacred song" , "What's heard in church" , "Church song" , "Lamps (anag) -- song" .)