It's cold, alas, back at Land's End (5)
I believe the answer is:
salad
'it's cold' is the definition.
I can't tell whether this defines the answer.
'alas back at land's end' is the wordplay.
'back' is a reversal indicator.
'at' is a charade indicator (letters next to each other).
'end' indicates one should take the final letters.
The final letter of 'land' is 'd'.
'alas' written backwards gives 'sala'.
'sala'+'d'='SALAD'
Can you help me to learn more?
(Other definitions for salad that I've seen before include "One may well be green" , "- Days (musical)" , "Cold dish of veg and herbs" , "A cold meal with lots of lettuce" , "One that may be dressed for dinner" .)