Bookishness demonstrated when they scorn hikes to mess around with subatomic particles (6)

'subatomic particles' is the definition.
(I've seen this in another clue)

'bookishness demonstrated when they scorn hikes to mess around' is the wordplay.
I cannot really see how this works, but
'when' could be 'on' (I've seen this in other clues) and 'on' is found within the answer.
'around' could be 'o' (a round letter) and 'o' is located in the answer.
The remaining letters 'bss' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).

'with' is the link.

Can you help me to learn more?