Hope to let elements of a lens (9)
I believe the answer is:
telephoto
'a lens' is the definition.
(telephoto lens is a kind of lens)
'hope to let elements' is the wordplay.
'elements' is an anagram indicator (the letters or elements of the word in a new order).
'hope'+'to'+'let'='hopetolet'
'hopetolet' anagrammed gives 'TELEPHOTO'.
'of' acts as a link.
(Other definitions for telephoto that I've seen before include "Long-distance lens" , "Long type of camera lens" , "Distant shooter" , "Magnifying lens in a camera" , "Kind of lens" .)