An English part, no longer Othello, for instance (6)
I believe the answer is:
exmoor
'an english part' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
'no longer othello for instance' is the wordplay.
'no longer' becomes 'ex' (prefix meaning former or onetime).
'othello for instance' becomes 'moor' (Shakespeare's Othello is a Moor).
'ex'+'moor'='EXMOOR'
Can you help me to learn more?
(Other definitions for exmoor that I've seen before include "where some ponies are found" , "Devon/Somerset region" , "National park in south-west England" , "English rural region" , "Lorna Doone country" .)