Assault a teetotaller at closing time in a bar (6)
I believe the answer is:
batter
'assault' is the definition.
(thesaurus)
'a teetotaller at closing time in a bar' is the wordplay.
'a teetotaller' becomes 'tt' (abbreviation).
'at' says to put letters next to each other.
'closing time' becomes 'e' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'in' indicates putting letters inside.
'tt'+'e'='tte'
'tte' put within 'bar' is 'BATTER'.
Can you help me to learn more?
(Other definitions for batter that I've seen before include "Flour and egg coating" , "Yorkshire pudding and cricket both require this" , "Strike with hard blows" , "Beat - coating used in frying food" , "Fritter coating" .)