Sacked tabloid editor supports newspaper, investing millions (5,6)

'sacked tabloid editor' is the definition.
(former editor of the Daily Mirror)

'supports newspaper investing millions' is the wordplay.
I cannot quite see how this works, but
'supports' could be 'piers' (pier is a kind of support) and 'piers' is found in the answer.
'newspaper' could be 'organ' (I've seen this in other clues) and 'organ' is found within the answer.
'millions' could be 'm' (abbreviation) and 'm' is present in the answer.
This accounts for all the letters.
This explanation may well be incorrect...