Mush something to chew over (3)
I believe the answer is:
mug
'mush' is the definition.
(thesaurus)
'something to chew over' is the wordplay.
'something to chew' becomes 'gum' (I've seen this in another clue).
'over' is a reversal indicator.
'gum' written backwards gives 'MUG'.
(Other definitions for mug that I've seen before include "Gullible person" , "Drinking vessel, by gum" , "Vessel for a bit of a fool" , "Idiot" , "Tankard" .)