Fairy gets small opportunities for viewing devices (10)

'viewing devices' is the definition.
'periscopes' can be an answer for 'devices' (periscope is a kind of device). I'm not sure about the 'viewing' bit.

'fairy gets small opportunities' is the wordplay.
'fairy' becomes 'peri' (Persian mythological being).
'gets' means one lot of letters go next to another.
'small opportunities' becomes 'scopes' (I can't explain this - if you can you should give a lot more credence to this answer).
'peri'+'scopes'='PERISCOPES'

'for' acts as a link.

Can you help me to learn more?