Understands and has the safety devices in action (7,2)

'understands' is the definition.
The answer and definition can be both related to thinking as well as being verbs in their -s form.
Perhaps they are linked in a way I don't understand?

'and has the safety devices in action' is the wordplay.
I cannot quite understand how this works, but
'and' could be 'n' (common abbreviation for 'and') and 'n' is present in the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is located in the answer.
'devices' could be 'caches' (cache is a kind of device) and 'caches' is found within the leftover letters.
A single letter 'o' remains which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?