Ice store - terribly abstruse (8)
I believe the answer is:
esoteric
'abstruse' is the definition.
(I've seen this in another clue)
'ice store terribly' is the wordplay.
'terribly' is an anagram indicator.
'ice'+'store'='icestore'
'icestore' is an anagram of 'ESOTERIC'.
(Other definitions for esoteric that I've seen before include "Tie score (anagram)" , "'Abstruse, arcane (8)'" , "Hard to understand" , "Intended for the few" , "unintelligible to outsiders" .)