Bacteriologist favoured upping radiation (5)
I believe the answer is:
petri
'bacteriologist' is the definition.
(I've seen this before)
'favoured upping radiation' is the wordplay.
'favoured' becomes 'pet' (as in a pet project).
'upping radiation' becomes 'ri' (I can't justify this - if you can you should believe this answer much more).
'pet'+'ri'='PETRI'
Can you help me to learn more?
(Other definitions for petri that I've seen before include "-- Dish, used for cultures" , "Scientist" , "Sort of dish" , "Cultures are grown in a -- dish" , "- - dish (science)" .)