He painted giant straddling island (6)
I believe the answer is:
titian
'he painted' is the definition.
(I've seen this before)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for titian that I've seen before include "Venetian fifteenth-sixteenth century painter" , "Colour named after artist" , "Painter, noted for works with bright auburn hair" , "Italian Old Master and colour" , "Reddish-gold; painter" .)