During school period little boy and I had to be ranked 'middling (12)
I believe the answer is:
intermediate
''middling' is the definition.
(thesaurus)
'during school period little boy and i had' is the wordplay.
'during' becomes 'in' (e.g. during February means in February).
'school period' becomes 'term' (I've seen this before).
'little boy' becomes 'Ed' (nickname or 'little' form of Edward).
'and' means one lot of letters go next to another.
'had' becomes 'ate' (e.g. I had an ice cream).
'in'+'term'+'ed'+'i'+'ate'='INTERMEDIATE'
'to be ranked' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for intermediate that I've seen before include "Coming between two things in some way" , "Act as agent" , "Coming between (eg, in size)" , "Lying between two extremes" .)