Whence, in Wales, a new hat is on the way (5)
I believe the answer is:
neath
'whence in wales' is the definition.
I know nothing about this answer so I can't tell whether this works.
'a new hat is on the way' is the wordplay.
'hat' suggests taking the first letters (I've seen 'hats' mean this (in a down clue, the letter at the top of the word)).
'is on' says to put letters next to each other.
'way' indicates anagramming the letters (another way of arranging the letters).
The first letter of 'new' is 'n'.
'a' put after 'n' is 'na'.
'na'+'the'='nathe'
'nathe' anagrammed gives 'NEATH'.
Can you help me to learn more?
(Other definitions for neath that I've seen before include "River" , "Under (poetic)" , "Welsh industrial town" , "town in South Wales" , "Under, poetically" .)