Tie in with return of The Cat in the Hat animation (6)
I believe the answer is:
attach
'tie in' is the definition.
'attach' can be an answer for 'tie' (to tie is to link or attach). I am not certain of the 'in' bit.
'return of the cat in the hat animation' is the wordplay.
'return of' is a reversal indicator.
'in' is an insertion indicator.
'animation' indicates an anagram (letters animated or moving).
'cat' backwards is 'tac'.
'hat' is an anagram of 'ath'.
'tac' going into 'ath' is 'ATTACH'.
'with' is the link.
Can you help me to learn more?
(Other definitions for attach that I've seen before include "Associate" , "Add or join to" , "Join to something else" , "Bind, fasten" , "Add on to, couple" .)