Try hat, scratching head with charm (7)
I believe the answer is:
attempt
'try' is the definition.
(I know that try can be written as attempt)
'hat scratching head with charm' is the wordplay.
'scratching head' means to remove the first letter (the word's head is removed).
'with' says to put letters next to each other.
'charm' becomes 'tempt' (synonyms).
'hat' with its initial letter taken away is 'at'.
'at'+'tempt'='ATTEMPT'
(Other definitions for attempt that I've seen before include "bash" , "Effort; go" , "Try, make an effort" , "Embark on, try" , "Have a crack" .)