Drink a large coffee at the outset before work more than once (7)
I believe the answer is:
alcopop
'drink' is the definition.
(type of alcoholic drink)
'a large coffee at the outset before work more than once' is the wordplay.
'at the outset' says to take the initial letters (the outset is the beginning).
'before' says to put letters next to each other.
'work' becomes 'op' (abbreviation for opus).
'more than once' says to double the letters.
The first letters of 'large coffee' is 'lc'.
'op' doubled is 'opop'.
'a'+'lc'+'opop'='ALCOPOP'
(Other definitions for alcopop that I've seen before include "drink favoured by youngsters" , "drink young people like" , "It tastes like a soft drink, but isn't!" , "Drink for young adults" , "Soft drink containing spirits" .)