Around 1st of January, wade across narrow inlet (5)
I believe the answer is:
fjord
'narrow inlet' is the definition.
(I've seen this in another clue)
'around 1st of january wade across' is the wordplay.
'around' indicates putting letters inside.
'1st of january' becomes 'J' (the first letter of the word 'January').
'wade across' becomes 'ford' (I've seen this in another clue).
'j' inserted inside 'ford' is 'FJORD'.
(Other definitions for fjord that I've seen before include "part of Norway" , "Sea inlet" , "Northern location?" , "Norwegian inlet (J, not I)" , "Rock-bound inlet" .)