Descending onto platform, edge forward, increasingly (7)

'forward increasingly' is the definition.
(more and more lippy)

'descending onto platform edge' is the wordplay.
'descending onto' is a charade indicator (letters next to each other) (in a down clue, some letters go on top of others).
'platform' becomes 'pier' (I have seen 'Coastal platform ' mean 'pier' so perhaps 'platform' could also mean 'pier').
'edge' becomes 'lip' (lip is a kind of edge**).
'pier' put after 'lip' is 'LIPPIER'.