Is able to get this mostly from the corner of one's eyes (6)
I believe the answer is:
canthi
'the corner of one's eyes' is the definition.
I know nothing about this answer so I can't tell whether it can be defined by this definition.
'is able to get this mostly' is the wordplay.
'is able to' becomes 'can' (if you can do something you are able to do it).
'get' means one lot of letters go next to another.
'mostly' means to remove the last letter.
'this' with its final letter taken off is 'thi'.
'can'+'thi'='CANTHI'
'from' is the link.
Can you help me to learn more?
(Another definition for canthi that I've seen is " corners of the eyes?".)