Take clergyman in case installing headstone causes a crack in the ice (8)
I believe the answer is:
crevasse
'headstone causes a crack in the ice' is the definition.
I can't judge whether this definition defines the answer.
'take clergyman in case installing' is the wordplay.
'take' becomes 's' (I can't justify this - if you can you should give a lot more credence to this answer).
'clergyman' becomes 'rev' (short for reverend).
'in' means one lot of letters goes inside another.
'installing' is an insertion indicator (inserted letters are installed).
'rev' placed into 'case' is 'crevase'.
's' going within 'crevase' is 'CREVASSE'.
Can you help me to learn more?
(Other definitions for crevasse that I've seen before include "climbing hazard in glacier" , "Deep glacial crack" , "opening" , "Crack in a mountain slope or a glacier" , "Deep fissure in a glacier" .)