Crossword Genius

Expert comes in to make smaller duplicate (9)

Ross

I believe the answer is:

reproduce

'duplicate' is the definition.
(I know that duplicate is a more specific form of reproduce)

'expert comes in to make smaller' is the wordplay.
'expert' becomes 'pro' (short for professional).
'comes in to' is an insertion indicator.
'make smaller' becomes 'reduce' (reducing is a kind of making smaller).
'pro' put inside 'reduce' is 'REPRODUCE'.

(Other definitions for reproduce that I've seen before include "Create offspring" , "To propagate" , "Ape" , "Make a child" , "achieve propagation" .)

I've seen this clue in The Daily Express.
Want a hint initially instead of a full solution? Install my app