Fly around tail-end of the sun (5)
I believe the answer is:
solar
'of the sun' is the definition.
(I've seen this before)
'fly around tail-end' is the wordplay.
'fly' becomes 'soar' (soaring is a kind of flying**).
'around' indicates putting letters inside.
'end' says to take the final letters.
The final letter of 'tail' is 'l'.
'soar' placed around 'l' is 'SOLAR'.
(Other definitions for solar that I've seen before include "Mediaeval chamber" , "Using the sun's energy" , "Pertaining to the sun" , "Of the sun, as ray or panel" , "of heavenly body" .)