Pleasantly destroyed lice in New York (6)
I believe the answer is:
nicely
'pleasantly' is the definition.
(I've seen this before)
'destroyed lice in new york' is the wordplay.
'destroyed' indicates anagramming the letters.
'in' is an insertion indicator.
'new york' becomes 'ny'.
'lice' anagrammed gives 'icel'.
'icel' placed inside 'ny' is 'NICELY'.
(Other definitions for nicely that I've seen before include "Agreeably, delightfully" , "'Amiably, pleasantly (6)'" , "In a pleasant way" , "Good-naturedly" , "Agreeably, respectably" .)