Group of students finally pay attention (4)
I believe the answer is:
year
'group of students' is the definition.
(I've seen this before)
'finally pay attention' is the wordplay.
'finally' suggests the final letters.
'attention' becomes 'ear' (having someone's ear is having their attention).
The final letter of 'pay' is 'y'.
'y'+'ear'='YEAR'
(Other definitions for year that I've seen before include "12 months" , "Period of revolution" , "Many students" , "Manage" , "365 or 366 days" .)