Sailors having a party on top deck (5)
I believe the answer is:
adorn
'deck' is the definition.
(I've seen this in another clue)
'sailors having a party on top' is the wordplay.
I cannot quite understand how this works, but
'sailors' could be 'rn' (abbreviation for Royal Navy) and 'rn' is located in the answer.
'a' is within the answer.
'party' could be 'do' (do can informally mean a party) and 'do' is found within the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for adorn that I've seen before include "get dressed!" , "Festoon" , "Embellish, decorate" , "dress" , "Improve appearance" .)