Very old retired sailors embraced by rowers instantly (9)
I believe the answer is:
overnight
'instantly' is the definition.
Both the answer and definition are adverbs. Perhaps you can see a link between them that I don't see?
'very old retired sailors embraced by rowers' is the wordplay.
'very old' becomes 'vo' (this could be a standard abbreviation of which I'm unaware).
'retired' is a reversal indicator.
'sailors' becomes 'RN' (abbreviation for Royal Navy).
'embraced by' indicates putting letters inside.
'rowers' becomes 'eight' (eight can mean a crew of eight rowers).
'vo' in reverse letter order is 'ov'.
'rn' inserted into 'eight' is 'ernight'.
'ov'+'ernight'='OVERNIGHT'
Can you help me to learn more?
(Other definitions for overnight that I've seen before include "Lasting from dusk to dawn" , "Very quickly" , "from one day to the next" , "Until morning; suddenly" , "until tomorrow" .)