Group initially believing Cockney’s intuition (5)
I believe the answer is:
bunch
'group' is the definition.
The answer is an example.
'initially believing cockney's intuition' is the wordplay.
'initially' suggests taking the first letters.
'cockney's intuition' becomes 'unch' ('hunch' - synonyms - said with the 'H' dropped - a cockney accent.).
The first letter of 'believing' is 'b'.
'b'+'unch'='BUNCH'
(Other definitions for bunch that I've seen before include "Posy (of picked flowers)" , "Small number of flowers tied together" , "Grouping of a number of similar things" , "A cluster, group" , "Small group of flowers or people" .)