Discovered discarding uranium to be foolishly impractical (4)
I believe the answer is:
fond
'be foolishly impractical' is the definition.
I can't judge whether this defines the answer.
'discovered discarding uranium' is the wordplay.
'discovered' becomes 'found' (to discover is to find).
'discarding' indicates named letters should be taken away.
'uranium' becomes 'U' (U is the chemical symbol for uranium).
'found' with 'u' taken out is 'FOND'.
'to' acts as a link.
Can you help me to learn more?
(Other definitions for fond that I've seen before include "Affectionate, maybe foolish" , "Partial to" , "Feeling affection, maybe foolish" , "Keen on; indulgent" , "Affectionate - tender" .)