Intensified or became more profound (8)
I believe the answer is:
deepened
I believe this clue is a double definition.
'intensified' is the first definition.
(deepening is a kind of intensifying)
'became more profound' is the second definition.
(I've seen this before)
(Other definitions for deepened that I've seen before include "Became more profound" , "Made more profound" , "Made more intense" .)