Boy rejected education and advanced slowly (5)
I believe the answer is:
nosed
'advanced slowly' is the definition.
'boy rejected education' is the wordplay.
'boy' becomes 'son' ('son' can be a synonym of 'boy'**).
'rejected' shows that the letters should be reversed in order.
'education' becomes 'ed' (abbreviation - e.g. sex ed).
'son' backwards is 'nos'.
'nos'+'ed'='NOSED'
'and' is the link.
(Other definitions for nosed that I've seen before include "Eased" , "edged out" , "Moved slowly and cautiously forward" , "Pried" , "See 1 Across" .)