Fellow’s free, away halfway day before weekend (6)
I believe the answer is:
friday
'day before weekend' is the definition.
(Friday is the day immediately before the weekend)
'fellow's free away halfway' is the wordplay.
'fellow' becomes 'F' (abbreviation - of a society etc.).
'free' becomes 'rid' (similar in meaning).
'halfway' suggests halving the letters.
'away' with half the letters taken is 'ay'.
'f'+'rid'+'ay'='FRIDAY'
(Other definitions for friday that I've seen before include "Day named after a Norse goddess" , "Its child is loving and giving" , "An islander" , "late in the week" , "The 13th is considered unlucky" .)