Pick fruit eating each tart, oddly (8)
I believe the answer is:
plectrum
'pick' is the definition.
(a guitar pick)
'fruit eating each tart oddly' is the wordplay.
'fruit' becomes 'plum' (plum is a kind of fruit).
'eating' indicates putting letters inside.
'oddly' indicates alternate letters (letters in the odd-numbered positions are used).
'each'+'tart'='eachtart'
The alternating letters of 'eachtart' are 'ectr'.
'plum' enclosing 'ectr' is 'PLECTRUM'.
(Other definitions for plectrum that I've seen before include "Small piece of plastic for plucking musical strings" , "Implement for plucking guitar strings" , "It's used to pluck, a guitar say" , "Guitar pick" , "Guitarist's implement" .)