Extremely short, short service for author (9)

I believe the answer is:

stevenson

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'for author' is the definition.
(novelist Robert Louis Stevenson)

'extremely short short service' is the wordplay.
'extremely short' becomes 'st' (I can't justify this - if you can you should believe this answer much more).
'short' means to remove the last letter.
'service' becomes 'evensong' (type of church service).
'evensong' with its last letter taken off is 'evenson'.
'st'+'evenson'='STEVENSON'

Can you help me to learn more?

(Other definitions for stevenson that I've seen before include "R L -, Kidnapped author" , "Robert Louis --, Scottish novelist" , "Author of 12 2" , "Writer of Treasure Island, d. 1894" , "Scottish writer" .)

I've seen this clue in The Times.

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