Samuel's teacher takes note of top class (5)
I believe the answer is:
elite
'top class' is the definition.
'samuel's teacher takes note' is the wordplay.
'samuel's teacher' becomes 'eli' (I've seen this before).
'takes' says to put letters next to each other.
'note' becomes 'te'.
'eli'+'te'='ELITE'
'of' is the link.
(Other definitions for elite that I've seen before include "A privileged or superior social group" , "A particular typesize" , "Chosen ones" , "A privileged class of people" , "Select part" .)