Here's awfully steep! (5)
I believe the answer is:
sheer
'steep' is the definition.
(similar in meaning)
'here's awfully' is the wordplay.
'awfully' is an anagram indicator.
'heres' with letters rearranged gives 'SHEER'.
(Other definitions for sheer that I've seen before include "needing to change a course" , "Very steep - may apply to 4" , "Utter - precipitous" , "Deviate (from) - vertical" , "Completely" .)