One working hard starts to subedit world-renowned books (4)
I believe the answer is:
swot
'one working hard' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'starts to subedit world-renowned books' is the wordplay.
'starts to' indicates taking the first letters.
'renowned books' becomes 'ot' (abbreviation for Old Testament. I am not sure about the 'renowned' bit.).
The first letters of 'subedit world' is 'sw'.
'sw'+'ot'='SWOT'
Can you help me to learn more?
(Other definitions for swot that I've seen before include "Hard worker" , "Mug up" , "Learner" , "Cram for exam" , "Of student, study hard" .)