Live together, initially counting on help slightly (7)
I believe the answer is:
cohabit
'live together' is the definition.
('cohabit' can be a synonym of 'live together')
'initially counting on help slightly' is the wordplay.
'initially' says to take the initial letters.
'slightly' becomes 'abit' (I've seen this before).
The first letters of 'counting on help' is 'coh'.
'coh'+'abit'='COHABIT'
(Other definitions for cohabit that I've seen before include "Live together as husband and wife" , "Live together, married or not" , "Share a property" , "become bedfellows" , "Share residence" .)