He painted innocents originally gobbled up by giant (6)
I believe the answer is:
titian
'he painted' is the definition.
(16th-century painter)
'innocents originally gobbled up by giant' is the wordplay.
'originally' suggests taking the first letters.
'gobbled up by' is an insertion indicator.
'giant' becomes 'titan' (synonyms).
The first letter of 'innocents' is 'i'.
'i' going within 'titan' is 'TITIAN'.
(Other definitions for titian that I've seen before include "Venetian old master, d. 1575" , "Italian Renaissance painter" , "Painter; red tint" , "Reddish-gold; painter" , "Painter, noted for works with bright auburn hair" .)