Old Roman firm at heart (4)
I believe the answer is:
cato
'old roman' is the definition.
(Roman politician)
'firm at heart' is the wordplay.
I cannot really understand how this works, but
'at' is within the answer.
'firm' could be 'co' (a firm is a company) and 'co' is found in the remaining letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for cato that I've seen before include "Roman statesman" , "Senator" , "Marcus Porcius - , Roman politician, censor" , "classical writer" , "Ancient Roman censor" .)