Students take turn during interval (4)
I believe the answer is:
lull
'interval' is the definition.
(lull is a kind of interval)
'students take turn during' is the wordplay.
'students' becomes 'LL' (two abbreviations for learner).
'take turn' becomes 'ul' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'during' means one lot of letters goes inside another.
'll' going around 'ul' is 'LULL'.
Can you help me to learn more?
(Other definitions for lull that I've seen before include "Short period of quiet" , "Short period of calm" , "Rock to sleep" , "Short spell of calm" , "Temporary calm or respite" .)