Odd creases around very deep fissure (8)
I believe the answer is:
crevasse
'deep fissure' is the definition.
(I've seen this in another clue)
'odd creases around very' is the wordplay.
'odd' indicates an anagram.
'around' indicates putting letters inside.
'very' becomes 'v' (abbreviation).
'creases' anagrammed gives 'creasse'.
'creasse' enclosing 'v' is 'CREVASSE'.
(Other definitions for crevasse that I've seen before include "climbing hazard in glacier" , "Deep glacial fissure" , "13 in a glacier" , "cold break" , "Deep glacial crack" .)