Careful old man at home with betting (11)
I believe the answer is:
painstaking
'careful' is the definition.
('painstaking' can be similar in meaning to 'careful')
'old man at home with betting' is the wordplay.
'old man' becomes 'pa' (both can mean father).
'at home' becomes 'in' ('in' can be similar in meaning to 'at home').
'with' says to put letters next to each other.
'betting' becomes 'staking' (staking is a kind of betting).
'pa'+'in'+'staking'='PAINSTAKING'
(Other definitions for painstaking that I've seen before include "Meticulous" , "Laboriously careful" , "Diligent, scrupulous" , "Assiduous, thorough" , "using great care" .)