Charge forced down in case of sale (8)
I believe the answer is:
stampede
'charge' is the definition.
(I've seen this before)
'forced down in case of sale' is the wordplay.
'forced down' becomes 'tamped' (I've seen this in another clue).
'in' is an insertion indicator.
'case of' suggests removing the centre (outsides of).
'sale' with its middle taken out is 'se'.
'tamped' placed inside 'se' is 'STAMPEDE'.
(Other definitions for stampede that I've seen before include "Wild run of frightened cattle" , "Panic-stricken charge of cattle" , "A flight of frightened cattle" , "herd scatter wildly" , "uncontrolled flight" .)