Appetisers in ship contain sour irregular pear (8)
I believe the answer is:
starters
'appetisers' is the definition.
(I've seen this before)
'ship contain sour irregular pear' is the wordplay.
'ship' becomes 'SS' (prefix in ship names eg SS Great Britain).
'contain' is an insertion indicator.
'sour' becomes 'tart' (similar in meaning).
'irregular pear' becomes 'er' (I can't justify this - if you can you should believe this answer much more).
'tart'+'er'='tarter'
'ss' placed around 'tarter' is 'STARTERS'.
'in' is the link.
Can you help me to learn more?
(Other definitions for starters that I've seen before include "officials at Aintree, say" , "First meal courses for beginners" , "Arts rest for beginners" , "Hors d'oeuvres, sometimes the first course" , "Competitors entered for a race" .)