On holiday, taking in New York regardless (6)
I believe the answer is:
anyway
'regardless' is the definition.
(thesaurus)
'on holiday taking in new york' is the wordplay.
'on holiday' becomes 'away' (I've seen this before).
'taking in' means one lot of letters goes inside another.
'new york' becomes 'ny'.
'away' placed around 'ny' is 'ANYWAY'.
(Other definitions for anyway that I've seen before include "Regardless" , "Still" , "In any event" , "nevertheless, no matter what" , "At any rate" .)