So you went to school, dear man! (3,3)

I believe the answer is:

old boy

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'man' is the definition.
(I know that old boy is a type of man)

I can't explain the remainder of the clue.

(Other definitions for old boy that I've seen before include "I say, it's a former school chum" , "Alumnus (with network)" , "Former member of a school" , "Male former pupil" , "Male ex-pupil" .)

I've seen this clue in the Evening Standard.

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