Popular poet starts to rhapsodise using mystical imagery (4)

I believe the answer is:

rumi

'popular poet' is the definition.
(13th-century Persian poet)

'starts to rhapsodise using mystical imagery' is the wordplay.
'starts to' suggests taking the first letters.
The first letters of 'rhapsodise using mystical imagery' is 'RUMI'.

I've seen this clue in The Guardian.

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