Hours wasted with heartless mob getting into shape (7)
I believe the answer is:
rhombus
'shape' is the definition.
(rhombus is a kind of shape)
'hours wasted with heartless mob' is the wordplay.
'wasted with' indicates anagramming the letters.
'heartless' means to remove the middle letters.
'mob' with its middle removed is 'mb'.
'hours' with its letters mixed up with 'mb' makes 'RHOMBUS'.
'getting into' acts as a link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for rhombus that I've seen before include "Large bottle; vessel with spout" , "Diamond-shaped figure" , "Equilateral parallelogram" , "Oblique-angled parallelogram" , "Quadrilateral with four equal sides" .)