Copious beer gets right to the heart (5)
I believe the answer is:
large
'copious' is the definition.
(I've seen this before)
'beer gets right to the heart' is the wordplay.
'beer' becomes 'lag' (I can't explain this - if you can you should believe this answer much more).
'gets' indicates putting letters inside (gets can mean captures or absorbs).
'right' becomes 'r' (common abbreviation).
'to the' becomes 'definitearticle' ('the' is the definite article in English).
'heart' says to take the centre.
The centre of 'definitearticle' is 'e'.
'lag' enclosing 'r' is 'larg'.
'larg'+'e'='LARGE'
(Other definitions for large that I've seen before include "Big - 5 down (anag)" , "Great being regal" , "Generous" , "Huge" , "Big, outsize" .)