Letters translated on unusual map provide illumination (6,4)
I believe the answer is:
street lamp
'illumination' is the definition.
(street lamps provide illumination)
'letters translated on unusual map' is the wordplay.
'translated' is an anagram indicator.
'on' is a charade indicator (letters next to each other).
'unusual' is an anagram indicator.
'letters' is an anagram of 'streetl'.
'map' anagrammed gives 'amp'.
'streetl'+'amp'='STREET LAMP'
'provide' is the link.
(Other definitions for street lamp that I've seen before include "Illumination on post" , "Glare coming from this" , "Pavement illuminator" , "Wayside light" .)