It's open to view (3)
I believe the answer is:
eye
'view' is the definition.
(I've seen this before)
'it's open' is the wordplay.
'it' becomes 'e' ('e' can mean 'electronic' which is similar to 'IT').
'open' becomes 'ye' (I can't explain this - if you can you should give a lot more credence to this answer).
'e'+'ye'='EYE'
'to' is the link.
Can you help me to learn more?
(Other definitions for eye that I've seen before include "One looks" , "Observe narrowly" , "See 1" , "It accommodates a pupil" , "where the pupil is seated" .)