Pest that can ruin a ship (5)
I believe the answer is:
aphis
'pest that' is the definition.
'aphis' can be an answer for 'pest' (I've seen this before). I am not sure about the rest of the definition.
'ruin a ship' is the wordplay.
'ruin' is an anagram indicator.
'a'+'ship'='aship'
'aship' with letters rearranged gives 'APHIS'.
'can' acts as a link.
Can you help me to learn more?
(Other definitions for aphis that I've seen before include "Sap-sucking garden pest" , "Greenfly" , "Small insect" , "sucker?" , "Plant louse" .)