Fat amateur sleuth with attitude (7)
I believe the answer is:
adipose
'fat' is the definition.
(similar in meaning)
'amateur sleuth with attitude' is the wordplay.
'amateur sleuth' becomes 'adi' (I can't justify this - if you can you should give a lot more credence to this answer).
'with' says to put letters next to each other.
'attitude' becomes 'pose' (attitude can mean a pose or stance).
'adi'+'pose'='ADIPOSE'
Can you help me to learn more?
(Other definitions for adipose that I've seen before include "Like a sort of fat" , "Of tissue, fatty in substance" , "Is a dope fat?" , "Relating to fat" , "Like fatty tissue" .)