Welfare payment covers pub that doesn't open for drink (6)
I believe the answer is:
double
'drink' is the definition.
(I have seen 'Large drink' mean 'double' so perhaps 'drink' could also mean 'double')
'welfare payment covers pub that doesn't open' is the wordplay.
'welfare payment' becomes 'dole' (I can't explain this - if you can you should give a lot more credence to this answer).
'covers' means one lot of letters goes inside another.
'that doesn't open' means to remove the first letter.
'pub' with its initial letter taken off is 'ub'.
'dole' placed around 'ub' is 'DOUBLE'.
'for' is the link.
Can you help me to learn more?
(Other definitions for double that I've seen before include "With two equal parts" , "Make twice as many" , "Twin, dual" , "Offence of leaving one's car where it blocks another" , "Bed for two people" .)