Put too much in round barrel before getting in (7)
I believe the answer is:
overeat
'put too much in' is the definition.
'round barrel before getting in' is the wordplay.
'round' becomes 'o' (round can mean a round object**).
'barrel' becomes 'vat' (I've seen this before).
'before' becomes 'ere' (usually literary).
'getting in' indicates putting letters inside.
'vat' placed around 'ere' is 'vereat'.
'o'+'vereat'='OVEREAT'
(Other definitions for overeat that I've seen before include "Gorge oneself" , "Indulge in gluttony" , "Be greedy" , "pig out?" , "ignore threat of a big corporation?" .)