Preserve the best lean cut (6)
I believe the answer is:
pickle
'preserve' is the definition.
(I know this)
'best lean cut' is the wordplay.
'best' becomes 'pick' (the best possible pick or selection).
'lean cut' becomes 'le' (I can't justify this - if you can you should believe this answer much more).
'pick'+'le'='PICKLE'
'the' acts as a link.
Can you help me to learn more?
(Other definitions for pickle that I've seen before include "Preserve in brine or vinegar" , "Preserve; mess" , "Mischief-maker" , "A preserved vegetable or a fine mess" , "Marinate" .)