Hindu deity turning round old boat (5)
I believe the answer is:
aviso
'old boat' is the definition.
(historical type of boat)
'hindu deity turning round' is the wordplay.
'hindu deity' becomes 'siva' (Siva is an example).
'turning' is a reversal indicator.
'round' becomes 'o' (round can mean a round object).
'siva' back-to-front is 'avis'.
'avis'+'o'='AVISO'
(Other definitions for aviso that I've seen before include "Information" , "vessel carrying a message" .)