Poetic frequency (3)
I believe the answer is:
oft
'poetic frequency' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for oft that I've seen before include "Frequently, as the poet would have it" , "(In poetry) frequently" , "Consistently" , "Many a time to the poet." , "Frequently (poetic)" .)