Divinity’s welcomed by the cardinal (5)
I believe the answer is:
'cardinal' is the definition.
(three is a cardinal number)
'divinity's welcomed by the' is the wordplay.
'divinity' becomes 'Re' (Re is an example).
'welcomed by' is an insertion indicator (letters welcomed inside).
're' going inside 'the' is 'THREE'.
(Other definitions for three that I've seen before include "Feet in 3 Down" , "Subject of 1 9" , "Small number that still makes a crowd?" , "So many 12s today" , "Number of strikes before you're out" .)