The point of this device may not be apparent (6,3)
I believe the answer is:
safety pin
'the point of this device may not be apparent' is the definition.
'safety pin' can be an answer for 'device' (safety pin is a kind of device). I'm not certain of the rest of the definition.
'the point of this device' is the wordplay.
'the point of' becomes 'safety' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'this device' becomes 'pin' (pin is a kind of device).
'safety'+'pin'='SAFETY-PIN'
Can you help me to learn more?
(Other definitions for safety pin that I've seen before include "Fix them with this!" , "This should not be removed" , "Metal fastener" , "explosive feature?" , "Fastening device with protective catch" .)