Wrote about nothing when back on the ship (5)
I believe the answer is:
liner
'the ship' is the definition.
(liner is a kind of ship)
'wrote about nothing when back on' is the wordplay.
'wrote about' is a reversal indicator (I've seen 'written about' mean this).
'nothing' becomes 'nil' (eg nil is zero in football).
'when back' becomes 'er' (I can't justify this - if you can you should give a lot more credence to this answer).
'on' is a charade indicator (letters next to each other).
'nil' reversed gives 'lin'.
'lin'+'er'='LINER'
Can you help me to learn more?
(Other definitions for liner that I've seen before include "Passenger transport" , "reinforcement" , "eg QE2" , "Large passenger-ship" , "Large passenger vessel" .)