Two saw a drunk heading for yacht -- one hiding on it
I believe the answer is:
stowaway
'one hiding on it' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'two saw a drunk heading for yacht' is the wordplay.
'drunk' is an anagram indicator.
'heading for' suggests taking the first letters.
The first letter of 'yacht' is 'y'.
'two'+'saw'+'a'='twosawa'
'twosawa' with letters rearranged gives 'stowawa'.
'stowawa'+'y'='STOWAWAY'
Can you help me to learn more?
(Other definitions for stowaway that I've seen before include "Illegal ship's passenger" , "Hidden passenger" , "Non-fare paying traveller at sea" , "Unauthorised passenger" , "One illegally on board" .)