A scam involving introduction of ripe fruit (5)
I believe the answer is:
acorn
'fruit' is the definition.
(acorn is a kind of fruit)
'a scam involving introduction of ripe' is the wordplay.
'scam' becomes 'con' (I've seen this before).
'involving' means one lot of letters goes inside another.
'introduction of' says to take the initial letters.
The initial letter of 'ripe' is 'r'.
'con' placed around 'r' is 'corn'.
'a'+'corn'='ACORN'
(Other definitions for acorn that I've seen before include "cup's content" , "Tree seed" , "Potential oak" , "Nut of oak tree" , "form of seeding" .)