When some of the vessels are wrecked, there aren't so many (4)
I believe the answer is:
less
'there aren't so many' is the definition.
I can't tell whether this defines the answer.
'when some of the vessels are wrecked' is the wordplay.
'when' becomes 'l' (I can't explain this - if you can you should believe this answer much more).
'some of' indicates the central letters (I've seen 'some' mean this).
'are wrecked' is an anagram indicator.
The middle of 'vessels' is 'sse'.
'sse' anagrammed gives 'ess'.
'l'+'ess'='LESS'
Can you help me to learn more?
(Other definitions for less that I've seen before include "inferior" , "Fewer in number" , "A smaller amount" , "minor" , "Fewer; minus" .)