Sailor recalled terrible night in the sea (7)
I believe the answer is:
bathing
'the sea' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'sailor recalled terrible night' is the wordplay.
'sailor' becomes 'ab' (abbreviation for able seaman).
'recalled' shows that the letters should be reversed in order (to recall can mean to bring something back).
'terrible' indicates an anagram.
'ab' written backwards gives 'ba'.
'night' with letters rearranged gives 'thing'.
'ba'+'thing'='BATHING'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for bathing that I've seen before include "Taking a dip" , "Wallowing" , "Washing by immersion" .)