Treasurer in charge of old sailors' hats (8)

'hats' is the definition.
(tricorn is a kind of hat)

'treasurer in charge of old sailors'' is the wordplay.
I cannot quite see how this works, but
'of' could be 'o' and 'o' is found in the answer.
'sailors'' could be 'rn' (abbreviation for Royal Navy) and 'rn' is found in the answer.
'in charge' could be 'ic' (abbreviation for 'in charge') and 'ic' is present in the answer.
The remaining letters 'trs' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?