Soldier sick in bloody tube on island! (12)
I believe the answer is:
artilleryman
'soldier' is the definition.
(I've seen this before)
'sick in bloody tube on island' is the wordplay.
'sick' becomes 'ill' ('ill' can be a synonym of 'sick').
'in' indicates putting letters inside.
'bloody tube' becomes 'artery' (tube carrying blood).
'on' means one lot of letters go next to another.
'island' becomes 'man' (Man is an example**).
'ill' put into 'artery' is 'artillery'.
'artillery'+'man'='ARTILLERYMAN'
(Other definitions for artilleryman that I've seen before include "He's going to shoot" , "Soldier" , "Gunner" .)