Something explosive seen regularly in class (7)
I believe the answer is:
grenade
'something explosive' is the definition.
I can't tell whether this defines the answer.
'seen regularly in class' is the wordplay.
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
'in' is an insertion indicator.
'class' becomes 'grade' (grading is a kind of classing).
The alternating letters of 'seen' are 'en'.
'en' put into 'grade' is 'GRENADE'.
Can you help me to learn more?
(Other definitions for grenade that I've seen before include "Hand-thrown explosive" , "Small explosive device" , "Missile thrown" , "ultimate weapon" , "Small hand missile" .)