In the sun, soar round the central pylon (5)
I believe the answer is:
solar
'in the sun' is the definition.
(solar means relating to the sun)
'soar round the central pylon' is the wordplay.
'round' means one lot of letters goes inside another.
'the central' indicates the central letters.
The middle letter of 'pylon' is 'l'.
'soar' enclosing 'l' is 'SOLAR'.
(Other definitions for solar that I've seen before include "Using the sun's energy" , "room" , "chamber in old house" , "Using the energy of the sun" , "of heavenly body" .)