Bats I let on ark, large ship (3,6)
I believe the answer is:
oil tanker
'large ship' is the definition.
'oil tanker' can be an answer for 'ship' (I've seen this before). I'm unsure of the 'large' bit.
'bats i let on ark' is the wordplay.
'bats' indicates anagramming the letters (slang for mad).
'i'+'let'+'on'+'ark'='iletonark'
'iletonark' anagrammed gives 'OIL-TANKER'.
Can you help me to learn more?
(Other definitions for oil tanker that I've seen before include "On which crude" , "Fuel transporter" , "Ship carrying "black gold"" , "craft" , "boat" .)