Observe learner keeping quiet — backward type interacting weakly (6)
I believe the answer is:
lepton
'type interacting weakly' is the definition.
I can't tell whether this defines the answer.
'observe learner keeping quiet backward' is the wordplay.
'observe' becomes 'note' (synonyms).
'learner' becomes 'l' (as in a learner driver with L-plates on their car).
'keeping' indicates putting letters inside (some letters kept inside).
'quiet' becomes 'p' (music symbol for 'piano', ie soft or quiet).
'backward' shows that the letters should be reversed in order.
'note'+'l'='notel'
'notel' going around 'p' is 'notpel'.
'notpel' backwards is 'LEPTON'.
Can you help me to learn more?
(Another definition for lepton that I've seen is " Subatomic particle".)