Staff could occasionally come together (6)
I believe the answer is:
cudgel
'staff' is the definition.
(I have seen 'Heavy staff' mean 'cudgel' so perhaps 'staff' could also mean 'cudgel')
'could occasionally come together' is the wordplay.
'occasionally' means one should take alternating letters.
'come together' becomes 'gel' (gel can mean to go together well).
The alternating letters of 'could' are 'cud'.
'cud'+'gel'='CUDGEL'
(Other definitions for cudgel that I've seen before include "Short thick stick used as weapon" , "Heavy staff used as a weapon" , "brain" , "(Strike with a) heavy stick" , "Heavy stick or club as a weapon" .)