Functions with an introduction to social intimacy (8)
I believe the answer is:
cosiness
'social intimacy' is the definition.
'cosiness' can be an answer for 'intimacy' (I've seen this before). I'm not sure about the 'social' bit.
'functions with an introduction to' is the wordplay.
'functions' becomes 'cosines' (cosine is a kind of function).
'with' is a charade indicator (letters next to each other).
'an introduction to' becomes 's' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'cosines'+'s'='COSINESS'
Can you help me to learn more?
(Other definitions for cosiness that I've seen before include "comfortable feeling" , "Intimacy" , "Warm quality" , "Snug quality" , "Comfort, warmth" .)