It's insensitive to call us out for nothing (7)
I believe the answer is:
callous
'it's insensitive' is the definition.
(similar in meaning)
'call us out for nothing' is the wordplay.
'out' means one lot of letters goes inside another.
'for nothing' becomes 'o' (I can't justify this - if you can you should believe this answer much more).
'call'+'us'='callus'
'callus' placed around 'o' is 'CALLOUS'.
'to' is the link.
Can you help me to learn more?
(Other definitions for callous that I've seen before include "Hard and unfeeling" , "Insensitive, cruel" , "Not feeling" , "Emotionally hardened" , "Cruel or unsympathetic" .)