Injured lady heartlessly, without much thought (4)
I believe the answer is:
idly
'without much thought' is the definition.
(as in idly wondering something)
'injured lady heartlessly' is the wordplay.
'injured' becomes 'id' (I can't justify this - if you can you should give a lot more credence to this answer).
'heartlessly' means to remove the middle letters.
'lady' with its centre taken out is 'ly'.
'id'+'ly'='IDLY'
(Other definitions for idly that I've seen before include "In a lazy way" , "in a careless manner" , "So lacking purpose" , "without thinking" , "How people may stand by" .)