Cap a chap out East (5)

I believe the answer is:

beret

I'm a little stuck... Click here to teach me more about this clue!

'cap' is the definition.
(I know that beret is a type of cap)

'a chap out east' is the wordplay.
'a chap' becomes 'Ber'.
'out east' becomes 'et' (I can't explain this - if you can you should give a lot more credence to this answer).
'ber'+'et'='BERET'

Can you help me to learn more?

(Other definitions for beret that I've seen before include "Round, brimless cap" , "French style cap" , "cover for commandos" , "French-style hat" , "Basque headgear" .)

I've seen this clue in the Evening Standard.

Want a hint initially instead of a full solution? Install my app