Jeweller's magnifying glass (5)
I believe the answer is:
loupe
'jeweller's magnifying glass' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for loupe that I've seen before include "instrument in view of fine work" , "Jeweller's magnifying glass" , "Jeweller's eyeglass" , "Jeweller's eyepiece" .)