Conscientious dad not out placing bets? (11)
I believe the answer is:
painstaking
'conscientious' is the definition.
(I know that conscientious can be written as painstaking)
'dad not out placing bets?' is the wordplay.
'dad' becomes 'pa' (both can mean one's father).
'not out' becomes 'in' ('in' is the opposite to 'out').
'placing bets?' becomes 'staking' (as in staking money on something).
'pa'+'in'+'staking'='PAINSTAKING'
(Other definitions for painstaking that I've seen before include "Extremely careful" , "Meticulous" , "Assiduous, thorough" , "Diligent, scrupulous" , "Laboriously careful" .)