Caught up in Aristotelian nursery group (4)
I believe the answer is:
tots
'caught up' is the definition.
Although both the answer and definition are verbs, they are not in the same form of the verb.
'in aristotelian nursery group' is the wordplay.
'in' indicates putting letters inside.
'aristotelian nursery' becomes 'tts' (I can't justify this - if you can you should give a lot more credence to this answer).
'group' becomes 'o' (O is an example).
'tts' placed around 'o' is 'TOTS'.
Can you help me to learn more?
(Other definitions for tots that I've seen before include "Party drinks" , "Adds up for the youngsters" , "Adds up like small children" , "little people" , "Sailors' drams" .)