Second drink, dry, not right for regular (6)
I believe the answer is:
steady
'regular' is the definition.
(I know that regular can be written as steady)
'second drink dry not right' is the wordplay.
'second' becomes 's' (common abbreviation).
'drink' becomes 'tea' (tea is a drink).
'not' is a deletion indicator.
'right' becomes 'r' (abbreviation).
'dry' with 'r' taken out is 'dy'.
's'+'tea'+'dy'='STEADY'
'for' is the link.
(Other definitions for steady that I've seen before include "Unfluctuating" , "Poised" , "On an even keel" , "Regular date" , "Stable - boyfriend or girlfriend" .)