Group meeting brave man with a swelling (8)
I believe the answer is:
ganglion
'a swelling' is the definition.
(I've seen this before)
'group meeting brave man' is the wordplay.
'group' becomes 'gang' (gang is a kind of group**).
'meeting' says to put letters next to each other.
'brave man' becomes 'lion'.
'gang'+'lion'='GANGLION'
'with' is the link.
(Other definitions for ganglion that I've seen before include "centre of interest" , "Collection of nerve cells" , "Swelling" , "Group of nerve cells from which fibres radiate" , "Nerve centre" .)