Royal direction to have a feast (6)
I believe the answer is:
regale
'a feast' is the definition.
(regale can mean to feast)
'royal direction' is the wordplay.
'royal' becomes 'regal' (synonyms).
'direction' becomes 'e' (E is an example).
'regal'+'e'='REGALE'
'to have' acts as a link.
(Other definitions for regale that I've seen before include "Entertain royally" , "Entertain, delight" , "Lavishly supply" , "Supply copiously" , "Feast, give pleasure to" .)