Lass there, awfully cruel (9)
I believe the answer is:
heartless
'cruel' is the definition.
('heartless' can be similar in meaning to 'cruel')
'lass there awfully' is the wordplay.
'awfully' indicates anagramming the letters.
'lass'+'there'='lassthere'
'lassthere' is an anagram of 'HEARTLESS'.
(Other definitions for heartless that I've seen before include "Uncaring" , "Cold-blooded" , "with no concern for others?" , "Lacking feeling through cardiac deficiency" , "That's very cruel" .)