Hits insect on board ship (6)
I believe the answer is:
smites
'hits' is the definition.
(smiting is a kind of hitting)
'insect on board ship' is the wordplay.
'insect' becomes 'mite' (I can't explain this - if you can you should believe this answer much more).
'on board' indicates putting letters inside.
'ship' becomes 'ss'.
'mite' inserted into 'ss' is 'SMITES'.
Can you help me to learn more?
(Other definitions for smites that I've seen before include "Strikes heavily or kills, biblical word" , "biblical hits" , "Deals a heavy blow" .)