Maelstroms of rot developing in bad habits? (8)
I believe the answer is:
vortices
'maelstroms' is the definition.
(alternative plural of 'vortex')
'rot developing in bad habits?' is the wordplay.
'developing' indicates anagramming the letters (letters developed into a new form).
'in' indicates putting letters inside.
'bad habits?' becomes 'vices' (I've seen this before).
'rot' is an anagram of 'ort'.
'ort' placed inside 'vices' is 'VORTICES'.
'of' acts as a link.
(Other definitions for vortices that I've seen before include "Whirling masses (of air or liquid)" , "revolutionary movements" .)