Writer's block, age-weary every now and again (9)
I believe the answer is:
hemingway
'writer's' is the definition.
(Hemingway is an example)
'block age-weary every now and again' is the wordplay.
'block' becomes 'hemin' (I can't justify this - if you can you should give a lot more credence to this answer).
'every now and again' means one should take alternating letters.
'age'+'weary'='ageweary'
The alternating letters of 'ageweary' are 'gway'.
'hemin'+'gway'='HEMINGWAY'
Can you help me to learn more?
(Other definitions for hemingway that I've seen before include "See 5" , "Author of The Old Man and the Sea" , "Ernest --, US author" , "He wrote Farewell to Arms" , "Ernest . . . . . . . . . wrote 'For Whom the Bell Tolls'" .)