Northern university to remove sort of waste that’s harmful (7)
I believe the answer is:
nuclear
'sort of waste that's harmful' is the definition.
I can't judge whether this defines the answer.
'northern university to remove' is the wordplay.
'northern' becomes 'n' (abbreviation e.g. N. Ireland).
'university' becomes 'U' (abbreviation as in UMass).
'to' means one lot of letters go next to another.
'remove' becomes 'clear' (clearing is a kind of removing).
'n'+'u'+'clear'='NUCLEAR'
Can you help me to learn more?
(Other definitions for nuclear that I've seen before include "Relating to atomic cores" , "Relating to atomic energy" , "> certain WMDs" , "sort of family" , "small family?" .)