Meat in picnic basket half wasted (3)
I believe the answer is:
ham
'meat' is the definition.
(ham is a kind of meat)
'picnic basket half wasted' is the wordplay.
'picnic basket' becomes 'hamper' (as in a food hamper).
'half wasted' suggests halving the letters.
'hamper' with half the letters taken is 'HAM'.
'in' acts as a link.
(Other definitions for ham that I've seen before include "One of Noah's sons" , "Poor person acting" , "An actor who overdoes it in meaty way" , "Overacting actor" , "Flamboyant actor, meaty type" .)