Observe silicon and another element at work (3,2,2)
I believe the answer is:
sit in on
'observe' is the definition.
The definition and answer can be both related to thinking as well as being verbs in their base form.
Maybe you can see an association between them that I don't see?
'silicon and another element at work' is the wordplay.
'silicon' becomes 'Si' (Si is the chemical symbol for silicon).
'and' says to put letters next to each other.
'another element' becomes 'tin' (tin is a kind of element. I am not sure about the 'another' bit.).
'at work' becomes 'on' (on can mean activated or working).
'si'+'tin'+'on'='SIT IN ON'
Can you help me to learn more?
(Another definition for sit in on that I've seen is " Attend (a meeting)".)