Pet in need of attention, cast to the margins (6)

'pet' is the definition.
(I know that pet can be written as dearie)

'attention cast to the margins' is the wordplay.
'attention cast' becomes 'arie' (I can't explain this - if you can you should give a lot more credence to this answer).
'to' is a charade indicator (letters next to each other) (I've seen this in other clues).
'the' becomes 'definite article' ('the' is the definite article in English).
'margins' says to hollow out the word (remove centre letters) (the letters on the margins are used).
'definitearticle' with its middle taken out is 'de'.
'arie' after 'de' is 'DEARIE'.

'in need of' acts as a link.

Can you help me to learn more?