Train ophthalmologist, initially, to cut next to small pupils (10)
I believe the answer is:
schoolboys
'pupils' is the definition.
(I've seen this before)
'train ophthalmologist initially to cut next to small' is the wordplay.
'train' becomes 'school' (I've seen this before).
'ophthalmologist initially' becomes 'o' (I can't justify this - if you can you should give a lot more credence to this answer).
'to cut' is an insertion indicator.
'next to' becomes 'by'.
'small' becomes 's' (abbreviation - e.g. clothes size).
'o' placed within 'by' is 'boy'.
'school'+'boy'+'s'='SCHOOLBOYS'
Can you help me to learn more?
(Another definition for schoolboys that I've seen is " pupils".)