In New York, as CIA need to move carefully (4)
'carefully' is the definition.
'in new york as cia need to move' is the wordplay.
'in' is an insertion indicator.
'new york' becomes 'ny'.
'to move' indicates anagramming the letters.
'as'+'cia'+'need'='ascianeed'
'ascianeed' anagrammed gives 'iceandeas'.
'ny' enclosing 'iceandeas' is 'NICE AND EASY'.
(Another definition for nice and easy that I've seen is " what does it every time!)".)
'cia need to move carefully' is the definition.
I can't tell whether this defines the answer.
'in new york' is the wordplay.
'new' indicates an anagram.
'york' becomes 'ce' (I can't justify this - if you can you should give a lot more credence to this answer).
'in' is an anagram of 'ni'.
'ni'+'ce'='NICE'
'as' acts as a link.
(Other definitions for nice that I've seen before include "good" , "Pleasant, agreeable" , "Pleasant Riviera town?" , "French resort; kind" , "French seaport in SE - sounds pleasant" .)