Mean mum, all midriff muscle? (6)
I believe the answer is:
shabby
'mean' is the definition.
(thesaurus)
'mum all midriff muscle?' is the wordplay.
'mum' becomes 'sh' (both can mean 'keep quiet').
'all midriff muscle?' becomes 'abby' (I am not sure about this - if you are sure you should believe this answer much more).
'sh'+'abby'='SHABBY'
Can you help me to learn more?
(Other definitions for shabby that I've seen before include "Dingy; dishonourable" , "Old and threadbare" , "Scruffy; unfair" , "Showing signs of wear and tear" , "Ill-dressed - mean" .)