Friend initially mocking one’s attempt to supply fortune telling (9)
I believe the answer is:
palmistry
'fortune telling' is the definition.
(palmistry is a kind of fortune telling)
'friend initially mocking one's attempt to' is the wordplay.
'friend' becomes 'pal' (pal can mean a friend).
'initially' indicates taking the first letters.
'one's' becomes 'i's' (Roman numeral).
'attempt to' becomes 'try' (I've seen this in other clues).
The initial letter of 'mocking' is 'm'.
'pal'+'m'+'is'+'try'='PALMISTRY'
'supply' is the link.
(Other definitions for palmistry that I've seen before include "Fortune-telling from hands" , "way to see the future" , "Fortune-telling, otherwise known as chiromancy" , "Using hands to tell fortunes" , "Hand reading" .)