With spring, there's a final melting of the ice encasing it (7)
I believe the answer is:
elastic
'with spring' is the definition.
'elastic' can be an answer for 'spring' (thesaurus). I am not certain of the 'with' bit.
'there's a final melting of the ice encasing it' is the wordplay.
'there's' indicates putting letters inside (I've seen this in other clues).
'a final melting' becomes 'las' (I can't explain this - if you can you should believe this answer much more).
'of' indicates an anagram (the answer comes from or 'of' the letters).
'encasing' is an insertion indicator.
'it' becomes ''t' (abbreviation. e.g. in 'tis).
'ice' is an anagram of 'eic'.
'las' put into 'eic' is 'elasic'.
'elasic' placed around 't' is 'ELASTIC'.
Can you help me to learn more?
(Other definitions for elastic that I've seen before include "Narrow strip of rubber" , "Ductile" , "Springing back to shape after stretching" , "It's lace (anag.)" , "Pliable" .)