Sit next to monkey that's animated and tense (4)
I believe the answer is:
abut
'sit next to' is the definition.
(I've seen this in another clue)
'monkey that's animated and tense' is the wordplay.
I cannot quite understand how this works, but
'tense' could be 't' (grammatical abbreviation) and 't' is present in the answer.
The remaining letters 'abu' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for abut that I've seen before include "Adjoin, press up against" , "Impinge" , "Adjoin, be contiguous to" , "Touch (side of next building)" , "Join" .)