Poet fooling around endlessly (6)
I believe the answer is:
larkin
'poet' is the definition.
(Philip Larkin)
'fooling around endlessly' is the wordplay.
'around' says to take the centre.
'endlessly' becomes 'arkin' (I can't justify this - if you can you should believe this answer much more).
The middle letter of 'fooling' is 'l'.
'l'+'arkin'='LARKIN'
Can you help me to learn more?
(Other definitions for larkin that I've seen before include "Big Jim . . . . . . was a great trade union leader" , "Orchestral violins, violas, cellos and basses" , "Scheme" , "Cab" , "Hull librarian and poet, d. 1985" .)