Line of walkers crossing cold ground that's familiar (5)
I believe the answer is:
patch
'familiar' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'line of walkers crossing cold ground' is the wordplay.
I cannot quite understand how this works, but
'cold' could be 'c' (eg on taps) and 'c' is located in the answer.
'line' could be 'path' (path is a kind of line) and 'path' is found within the leftover letters.
No letters remain.
This explanation may well be incorrect...
'that's' acts as a link.
Can you help me to learn more?
(Other definitions for patch that I've seen before include "Piece of land, of mending material" , "Mend by adding fabric" , "Plot - piece of cloth - period" , "Mend with piece of material" , "Court plaster" .)