Python discovered in sediment (4)
I believe the answer is:
lees
'sediment' is the definition.
(lees is a kind of sediment)
'python discovered' is the wordplay.
'python' becomes 'cleese' (Monty Python member John Cleese).
'discovered' says to take the centre.
The central letters of 'cleese' are 'LEES'.
'in' is the link.
(Other definitions for lees that I've seen before include "Dregs of drink" , "Deposit" , "Wine dregs" , "Sediement or else" , "worst part" .)