Cleric finds uranium in box (6)
I believe the answer is:
curate
'cleric' is the definition.
(I've seen this before)
'uranium in box' is the wordplay.
'uranium' becomes 'U' (U is the chemical symbol for uranium).
'in' is an insertion indicator.
'box' becomes 'crate' (crate is a kind of box).
'u' inserted into 'crate' is 'CURATE'.
'finds' is the link.
(Other definitions for curate that I've seen before include "Member of the clergy" , "A truce (anag)" , "assistant rector" , "Assistant to a parish priest" , "one wearing dog-collar" .)