Take the middle bit from the best stuff (4)
I believe the answer is:
cram
'stuff' is the definition.
(cramming is a kind of stuffing)
'take the middle bit from the best' is the wordplay.
'take the middle bit from' suggests removing the centre.
'the best' becomes 'cream' (I've seen this before).
'cream' with its middle removed is 'CRAM'.
(Other definitions for cram that I've seen before include "Crowd or pack to capacity" , "Greedily eat" , "Swot (for exam)" , "Quickly learn - stuff" , "Press together" .)