Cross as a beheaded buccaneer? (5)
I believe the answer is:
irate
'cross' is the definition.
(I've seen this before)
'a beheaded buccaneer?' is the wordplay.
'a beheaded' means to remove the first letter (the head of the word is removed).
'buccaneer?' becomes 'pirate' (synonyms).
'pirate' with its first letter taken away is 'IRATE'.
'as' acts as a link.
(Other definitions for irate that I've seen before include "Cross, irritated" , "become irritated" , "Extremely angry" , "Angry - furious" , "having got in wax" .)