Well then, cure is to be developed (6)
I believe the answer is:
source
'well' is the definition.
(I've seen this before)
'then cure is to be developed' is the wordplay.
'then' becomes 'so' (both can mean 'therefore' or 'in that case').
'is to be developed' is an anagram indicator.
'cure' with letters rearranged gives 'urce'.
'so'+'urce'='SOURCE'
(Other definitions for source that I've seen before include "Find" , "Spring, fountain head" , "Place or person where something begins" , "'Origin, root (6)'" , "Origin, starting-point" .)