Prepare the way for metal pot somehow to hold uranium (4,2,2)
I believe the answer is:
lead up to
'prepare the way for' is the definition.
(I've seen this in another clue)
'metal pot somehow to hold uranium' is the wordplay.
'metal' becomes 'lead' (lead is a kind of metal).
'somehow' is an anagram indicator.
'to hold' is an insertion indicator.
'uranium' becomes 'U' (U is the chemical symbol for uranium).
'pot' with letters rearranged gives 'pto'.
'pto' going around 'u' is 'upto'.
'lead'+'upto'='LEAD UP TO'
(Other definitions for lead up to that I've seen before include "Anticipate" , "Serve as introduction to or preparation for" , "prepare in stages" , "Gradually approach" , "Serve as preparation, or direct conversation towards" .)