Colossus inspiring one painter (6)
I believe the answer is:
titian
'painter' is the definition.
(Titian is an example)
'colossus inspiring one' is the wordplay.
'colossus' becomes 'titan' (both can mean something very big).
'inspiring' is an insertion indicator.
'one' becomes 'i' (Roman numeral).
'titan' going around 'i' is 'TITIAN'.
(Other definitions for titian that I've seen before include "Venetian fifteenth-sixteenth century painter" , "Reddish-gold; painter" , "painting" , "Italian artist" , "Venetian Renaissance painter" .)