Very late coming in, sees twitchy cat (7)
I believe the answer is:
siamese
'cat' is the definition.
(I know that Siamese is a type of cat)
'very late coming in sees twitchy' is the wordplay.
'very late coming' becomes 'iam' (I can't explain this - if you can you should give a lot more credence to this answer).
'in' indicates putting letters inside.
'twitchy' is an anagram indicator (I've seen this in other clues).
'sees' with letters rearranged gives 'sese'.
'iam' going within 'sese' is 'SIAMESE'.
Can you help me to learn more?
(Other definitions for siamese that I've seen before include "Pugnacious aquarium species -- shagginess, if I'm thief (anag)" , "Cat with slanting blue eyes and pale fur with darker points" , "like a cat" , "sort of twins" , "Pale breed of cat" .)