31 (1.5d) Book featuring David the poet's realm and Burnley's endless potential
It's one of the 'undefined' clues

I do them online from the website

I've filled up the top two thirds, but the bottom R hand corner is still blank, including the word that links all the defined clues. (Don't tell me)

I like Araucaria, they can be mystifying until you find the link, then, as Brain and Dave, said they are satisfying and not too hard.