Many leave fruit in addition (4)

I believe the answer is:

plus

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'addition' is the definition.
(I know this)

'many leave fruit in' is the wordplay.
'many' becomes 'l'.
'leave fruit' becomes 'pus' (I am not sure about this - if you are sure you should believe this answer much more).
'in' is an insertion indicator.
'l' placed within 'pus' is 'PLUS'.

Can you help me to learn more?

(Other definitions for plus that I've seen before include "asset" , "To the French it's more" , "advantageous" , "mark for arithmetic" , "Additional" .)

I've seen this clue in The Irish Independent.

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