Boffin, for example, good leader (7)
I believe the answer is:
egghead
'boffin' is the definition.
(I've seen this before)
'example good leader' is the wordplay.
'example' becomes 'eg' (short for 'exempli gratia', 'for example' in Latin).
'good' becomes 'g' (abbreviation).
'leader' becomes 'head' (head is a kind of leader).
'eg'+'g'+'head'='EGGHEAD'
'for' is the link.
(Other definitions for egghead that I've seen before include "Cracked" , "An intellectual (inf.)" , "may take a bashing at the breakfast table" , "brain" , "Informal intellectual of ovoid type" .)