Second of this month (7)
I believe the answer is:
instant
I believe this is a double definition.
'second' is the first definition.
('instant' can be a synonym of 'second')
'this month' is the second definition.
(I've seen this before)
'of' is the link.
(Other definitions for instant that I've seen before include "Brief moment" , "Immediate; moment in time" , "Trice" , "Without delay - short time" , "pressing" .)