500 on ship wear clothes (5)
I believe the answer is:
dress
'wear clothes' is the definition.
'dress' can be an answer for 'clothes' (dress is a kind of clothes). I am not certain of the 'wear' bit.
'500 on ship' is the wordplay.
'500' becomes 'D' (Roman numeral for 500).
'on' becomes 're' ('on' can be mean 'with reference to').
'ship' becomes 'SS' (prefix in ship names eg SS Great Britain).
'd'+'re'+'ss'='DRESS'
Can you help me to learn more?
(Other definitions for dress that I've seen before include "Garb" , "Put on one's clothes" , "This circle is the first gallery in a theatre" , "Uniform" , "For display, arrange" .)