Person whose job is summarising a short book or penning small treatise (10)

'person' is the definition.
(abstractor is a kind of person)

'a short book or penning small treatise' is the wordplay.
'short book' becomes 'b' (abbreviation for book; 'short' suggests an abbreviation).
'penning' indicates putting letters inside.
'small' becomes 's' (abbreviation - e.g. clothes size).
'treatise' becomes 'tract' (tract is a kind of treatise).
'b'+'or'='bor'
's'+'tract'='stract'
'bor' going around 'stract' is 'bstractor'.
'a'+'bstractor'='ABSTRACTOR'

'whose job is summarising' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.

Can you help me to learn more?