At home, safe but not confident (8)
I believe the answer is:
insecure
'not confident' is the definition.
(I've seen this before)
'at home safe' is the wordplay.
'at home' becomes 'in' ('I'm in' can mean 'I'm at home').
'safe' becomes 'secure' (associated in meaning).
'in'+'secure'='INSECURE'
'but' is the link.
(Other definitions for insecure that I've seen before include "Sinecure for those lacking in confidence" , "Timid" , "Not safe or confident in oneself" , "Vulnerable" , "(Feeling) unsafe" .)