No longer available to a king (4)

I believe the answer is:

offa

'king' is the definition.
(I've seen this before)

'no longer available to a' is the wordplay.
'no longer available' becomes 'off' (I've seen this before).
'off'+'a'='OFFA'

(Other definitions for offa that I've seen before include "Mercian leader" , "Entrenched person" , "Eighth century king of Mercia" , "Dyke-building Mercian" , "King of Mercia, who may have built a dyke" .)

I've seen this clue in The Irish Independent.

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