Down at the bottom of the class, nowadays (3)
I believe the answer is:
sad
'down' is the definition.
(thesaurus)
'the bottom of the class nowadays' is the wordplay.
'the bottom of' indicates one should take the final letters.
'nowadays' becomes 'ad'.
The final letter of 'class' is 's'.
's'+'ad'='SAD'
'at' acts as a link.
(Other definitions for sad that I've seen before include "low" , "grey" , "Heavy-hearted" , "Regrettable" , "Sorrowful, unhappy" .)