School nowadays is miserable (3)
I believe the answer is:
sad
'miserable' is the definition.
('sad' can be similar in meaning to 'miserable')
'school nowadays' is the wordplay.
'school' becomes 's'.
'nowadays' becomes 'ad'.
's'+'ad'='SAD'
'is' is the link.
(Other definitions for sad that I've seen before include "Deplorable" , "Regrettable" , "upset" , "Effect of winter darkness" , "Unfortunate" .)