Free to take a girl out for the day (6)
I believe the answer is:
friday
'the day' is the definition.
'free to take a girl out' is the wordplay.
'free' becomes 'rid' (synonyms).
'to take a girl' becomes 'fay' (I am not sure about this - if you are sure you should believe this answer much more).
'out' indicates putting letters inside.
'rid' inserted inside 'fay' is 'FRIDAY'.
'for' is the link.
Can you help me to learn more?
(Other definitions for friday that I've seen before include "God is thanked for this" , "Defoe's character" , "Robinson Crusoe's manservant" , "Crusoe's Man (Defoe)" , "late in the week" .)